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  1. 19 8月, 2021 1 次提交
  3. 06 8月, 2021 1 次提交
    • T
      Bluetooth: defer cleanup of resources in hci_unregister_dev() · e0448092
      由 Tetsuo Handa 提交于 
      syzbot is hitting might_sleep() warning at hci_sock_dev_event() due to
calling lock_sock() with rw spinlock held [1].

It seems that history of this locking problem is a trial and error.

Commit b40df574 ("[PATCH] bluetooth: fix socket locking in
hci_sock_dev_event()") in 2.6.21-rc4 changed bh_lock_sock() to
lock_sock() as an attempt to fix lockdep warning.

Then, commit 4ce61d1c ("[BLUETOOTH]: Fix locking in
hci_sock_dev_event().") in 2.6.22-rc2 changed lock_sock() to
local_bh_disable() + bh_lock_sock_nested() as an attempt to fix the
sleep in atomic context warning.

Then, commit 4b5dd696 ("Bluetooth: Remove local_bh_disable() from
hci_sock.c") in 3.3-rc1 removed local_bh_disable().

Then, commit e305509e ("Bluetooth: use correct lock to prevent UAF
of hdev object") in 5.13-rc5 again changed bh_lock_sock_nested() to
lock_sock() as an attempt to fix CVE-2021-3573.

This difficulty comes from current implementation that
hci_sock_dev_event(HCI_DEV_UNREG) is responsible for dropping all
references from sockets because hci_unregister_dev() immediately
reclaims resources as soon as returning from
hci_sock_dev_event(HCI_DEV_UNREG).

But the history suggests that hci_sock_dev_event(HCI_DEV_UNREG) was not
doing what it should do.

Therefore, instead of trying to detach sockets from device, let's accept
not detaching sockets from device at hci_sock_dev_event(HCI_DEV_UNREG),
by moving actual cleanup of resources from hci_unregister_dev() to
hci_cleanup_dev() which is called by bt_host_release() when all
references to this unregistered device (which is a kobject) are gone.

Since hci_sock_dev_event(HCI_DEV_UNREG) no longer resets
hci_pi(sk)->hdev, we need to check whether this device was unregistered
and return an error based on HCI_UNREGISTER flag.  There might be subtle
behavioral difference in "monitor the hdev" functionality; please report
if you found something went wrong due to this patch.

Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1]
Reported-by: Nsyzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: e305509e ("Bluetooth: use correct lock to prevent UAF of hdev object")
Acked-by: NLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e0448092
  5. 03 8月, 2021 4 次提交
  7. 02 8月, 2021 2 次提交
  9. 29 7月, 2021 3 次提交
    • D
      bpf: Fix leakage due to insufficient speculative store bypass mitigation · 2039f26f
      由 Daniel Borkmann 提交于 
      Spectre v4 gadgets make use of memory disambiguation, which is a set of
techniques that execute memory access instructions, that is, loads and
stores, out of program order; Intel's optimization manual, section 2.4.4.5:

  A load instruction micro-op may depend on a preceding store. Many
  microarchitectures block loads until all preceding store addresses are
  known. The memory disambiguator predicts which loads will not depend on
  any previous stores. When the disambiguator predicts that a load does
  not have such a dependency, the load takes its data from the L1 data
  cache. Eventually, the prediction is verified. If an actual conflict is
  detected, the load and all succeeding instructions are re-executed.

af86ca4e ("bpf: Prevent memory disambiguation attack") tried to mitigate
this attack by sanitizing the memory locations through preemptive "fast"
(low latency) stores of zero prior to the actual "slow" (high latency) store
of a pointer value such that upon dependency misprediction the CPU then
speculatively executes the load of the pointer value and retrieves the zero
value instead of the attacker controlled scalar value previously stored at
that location, meaning, subsequent access in the speculative domain is then
redirected to the "zero page".

The sanitized preemptive store of zero prior to the actual "slow" store is
done through a simple ST instruction based on r10 (frame pointer) with
relative offset to the stack location that the verifier has been tracking
on the original used register for STX, which does not have to be r10. Thus,
there are no memory dependencies for this store, since it's only using r10
and immediate constant of zero; hence af86ca4e /assumed/ a low latency
operation.

However, a recent attack demonstrated that this mitigation is not sufficient
since the preemptive store of zero could also be turned into a "slow" store
and is thus bypassed as well:

  [...]
  // r2 = oob address (e.g. scalar)
  // r7 = pointer to map value
  31: (7b) *(u64 *)(r10 -16) = r2
  // r9 will remain "fast" register, r10 will become "slow" register below
  32: (bf) r9 = r10
  // JIT maps BPF reg to x86 reg:
  //  r9  -> r15 (callee saved)
  //  r10 -> rbp
  // train store forward prediction to break dependency link between both r9
  // and r10 by evicting them from the predictor's LRU table.
  33: (61) r0 = *(u32 *)(r7 +24576)
  34: (63) *(u32 *)(r7 +29696) = r0
  35: (61) r0 = *(u32 *)(r7 +24580)
  36: (63) *(u32 *)(r7 +29700) = r0
  37: (61) r0 = *(u32 *)(r7 +24584)
  38: (63) *(u32 *)(r7 +29704) = r0
  39: (61) r0 = *(u32 *)(r7 +24588)
  40: (63) *(u32 *)(r7 +29708) = r0
  [...]
  543: (61) r0 = *(u32 *)(r7 +25596)
  544: (63) *(u32 *)(r7 +30716) = r0
  // prepare call to bpf_ringbuf_output() helper. the latter will cause rbp
  // to spill to stack memory while r13/r14/r15 (all callee saved regs) remain
  // in hardware registers. rbp becomes slow due to push/pop latency. below is
  // disasm of bpf_ringbuf_output() helper for better visual context:
  //
  // ffffffff8117ee20: 41 54                 push   r12
  // ffffffff8117ee22: 55                    push   rbp
  // ffffffff8117ee23: 53                    push   rbx
  // ffffffff8117ee24: 48 f7 c1 fc ff ff ff  test   rcx,0xfffffffffffffffc
  // ffffffff8117ee2b: 0f 85 af 00 00 00     jne    ffffffff8117eee0 <-- jump taken
  // [...]
  // ffffffff8117eee0: 49 c7 c4 ea ff ff ff  mov    r12,0xffffffffffffffea
  // ffffffff8117eee7: 5b                    pop    rbx
  // ffffffff8117eee8: 5d                    pop    rbp
  // ffffffff8117eee9: 4c 89 e0              mov    rax,r12
  // ffffffff8117eeec: 41 5c                 pop    r12
  // ffffffff8117eeee: c3                    ret
  545: (18) r1 = map[id:4]
  547: (bf) r2 = r7
  548: (b7) r3 = 0
  549: (b7) r4 = 4
  550: (85) call bpf_ringbuf_output#194288
  // instruction 551 inserted by verifier    \
  551: (7a) *(u64 *)(r10 -16) = 0            | /both/ are now slow stores here
  // storing map value pointer r7 at fp-16   | since value of r10 is "slow".
  552: (7b) *(u64 *)(r10 -16) = r7           /
  // following "fast" read to the same memory location, but due to dependency
  // misprediction it will speculatively execute before insn 551/552 completes.
  553: (79) r2 = *(u64 *)(r9 -16)
  // in speculative domain contains attacker controlled r2. in non-speculative
  // domain this contains r7, and thus accesses r7 +0 below.
  554: (71) r3 = *(u8 *)(r2 +0)
  // leak r3

As can be seen, the current speculative store bypass mitigation which the
verifier inserts at line 551 is insufficient since /both/, the write of
the zero sanitation as well as the map value pointer are a high latency
instruction due to prior memory access via push/pop of r10 (rbp) in contrast
to the low latency read in line 553 as r9 (r15) which stays in hardware
registers. Thus, architecturally, fp-16 is r7, however, microarchitecturally,
fp-16 can still be r2.

Initial thoughts to address this issue was to track spilled pointer loads
from stack and enforce their load via LDX through r10 as well so that /both/
the preemptive store of zero /as well as/ the load use the /same/ register
such that a dependency is created between the store and load. However, this
option is not sufficient either since it can be bypassed as well under
speculation. An updated attack with pointer spill/fills now _all_ based on
r10 would look as follows:

  [...]
  // r2 = oob address (e.g. scalar)
  // r7 = pointer to map value
  [...]
  // longer store forward prediction training sequence than before.
  2062: (61) r0 = *(u32 *)(r7 +25588)
  2063: (63) *(u32 *)(r7 +30708) = r0
  2064: (61) r0 = *(u32 *)(r7 +25592)
  2065: (63) *(u32 *)(r7 +30712) = r0
  2066: (61) r0 = *(u32 *)(r7 +25596)
  2067: (63) *(u32 *)(r7 +30716) = r0
  // store the speculative load address (scalar) this time after the store
  // forward prediction training.
  2068: (7b) *(u64 *)(r10 -16) = r2
  // preoccupy the CPU store port by running sequence of dummy stores.
  2069: (63) *(u32 *)(r7 +29696) = r0
  2070: (63) *(u32 *)(r7 +29700) = r0
  2071: (63) *(u32 *)(r7 +29704) = r0
  2072: (63) *(u32 *)(r7 +29708) = r0
  2073: (63) *(u32 *)(r7 +29712) = r0
  2074: (63) *(u32 *)(r7 +29716) = r0
  2075: (63) *(u32 *)(r7 +29720) = r0
  2076: (63) *(u32 *)(r7 +29724) = r0
  2077: (63) *(u32 *)(r7 +29728) = r0
  2078: (63) *(u32 *)(r7 +29732) = r0
  2079: (63) *(u32 *)(r7 +29736) = r0
  2080: (63) *(u32 *)(r7 +29740) = r0
  2081: (63) *(u32 *)(r7 +29744) = r0
  2082: (63) *(u32 *)(r7 +29748) = r0
  2083: (63) *(u32 *)(r7 +29752) = r0
  2084: (63) *(u32 *)(r7 +29756) = r0
  2085: (63) *(u32 *)(r7 +29760) = r0
  2086: (63) *(u32 *)(r7 +29764) = r0
  2087: (63) *(u32 *)(r7 +29768) = r0
  2088: (63) *(u32 *)(r7 +29772) = r0
  2089: (63) *(u32 *)(r7 +29776) = r0
  2090: (63) *(u32 *)(r7 +29780) = r0
  2091: (63) *(u32 *)(r7 +29784) = r0
  2092: (63) *(u32 *)(r7 +29788) = r0
  2093: (63) *(u32 *)(r7 +29792) = r0
  2094: (63) *(u32 *)(r7 +29796) = r0
  2095: (63) *(u32 *)(r7 +29800) = r0
  2096: (63) *(u32 *)(r7 +29804) = r0
  2097: (63) *(u32 *)(r7 +29808) = r0
  2098: (63) *(u32 *)(r7 +29812) = r0
  // overwrite scalar with dummy pointer; same as before, also including the
  // sanitation store with 0 from the current mitigation by the verifier.
  2099: (7a) *(u64 *)(r10 -16) = 0         | /both/ are now slow stores here
  2100: (7b) *(u64 *)(r10 -16) = r7        | since store unit is still busy.
  // load from stack intended to bypass stores.
  2101: (79) r2 = *(u64 *)(r10 -16)
  2102: (71) r3 = *(u8 *)(r2 +0)
  // leak r3
  [...]

Looking at the CPU microarchitecture, the scheduler might issue loads (such
as seen in line 2101) before stores (line 2099,2100) because the load execution
units become available while the store execution unit is still busy with the
sequence of dummy stores (line 2069-2098). And so the load may use the prior
stored scalar from r2 at address r10 -16 for speculation. The updated attack
may work less reliable on CPU microarchitectures where loads and stores share
execution resources.

This concludes that the sanitizing with zero stores from af86ca4e ("bpf:
Prevent memory disambiguation attack") is insufficient. Moreover, the detection
of stack reuse from af86ca4e where previously data (STACK_MISC) has been
written to a given stack slot where a pointer value is now to be stored does
not have sufficient coverage as precondition for the mitigation either; for
several reasons outlined as follows:

 1) Stack content from prior program runs could still be preserved and is
    therefore not "random", best example is to split a speculative store
    bypass attack between tail calls, program A would prepare and store the
    oob address at a given stack slot and then tail call into program B which
    does the "slow" store of a pointer to the stack with subsequent "fast"
    read. From program B PoV such stack slot type is STACK_INVALID, and
    therefore also must be subject to mitigation.

 2) The STACK_SPILL must not be coupled to register_is_const(&stack->spilled_ptr)
    condition, for example, the previous content of that memory location could
    also be a pointer to map or map value. Without the fix, a speculative
    store bypass is not mitigated in such precondition and can then lead to
    a type confusion in the speculative domain leaking kernel memory near
    these pointer types.

While brainstorming on various alternative mitigation possibilities, we also
stumbled upon a retrospective from Chrome developers [0]:

  [...] For variant 4, we implemented a mitigation to zero the unused memory
  of the heap prior to allocation, which cost about 1% when done concurrently
  and 4% for scavenging. Variant 4 defeats everything we could think of. We
  explored more mitigations for variant 4 but the threat proved to be more
  pervasive and dangerous than we anticipated. For example, stack slots used
  by the register allocator in the optimizing compiler could be subject to
  type confusion, leading to pointer crafting. Mitigating type confusion for
  stack slots alone would have required a complete redesign of the backend of
  the optimizing compiler, perhaps man years of work, without a guarantee of
  completeness. [...]

From BPF side, the problem space is reduced, however, options are rather
limited. One idea that has been explored was to xor-obfuscate pointer spills
to the BPF stack:

  [...]
  // preoccupy the CPU store port by running sequence of dummy stores.
  [...]
  2106: (63) *(u32 *)(r7 +29796) = r0
  2107: (63) *(u32 *)(r7 +29800) = r0
  2108: (63) *(u32 *)(r7 +29804) = r0
  2109: (63) *(u32 *)(r7 +29808) = r0
  2110: (63) *(u32 *)(r7 +29812) = r0
  // overwrite scalar with dummy pointer; xored with random 'secret' value
  // of 943576462 before store ...
  2111: (b4) w11 = 943576462
  2112: (af) r11 ^= r7
  2113: (7b) *(u64 *)(r10 -16) = r11
  2114: (79) r11 = *(u64 *)(r10 -16)
  2115: (b4) w2 = 943576462
  2116: (af) r2 ^= r11
  // ... and restored with the same 'secret' value with the help of AX reg.
  2117: (71) r3 = *(u8 *)(r2 +0)
  [...]

While the above would not prevent speculation, it would make data leakage
infeasible by directing it to random locations. In order to be effective
and prevent type confusion under speculation, such random secret would have
to be regenerated for each store. The additional complexity involved for a
tracking mechanism that prevents jumps such that restoring spilled pointers
would not get corrupted is not worth the gain for unprivileged. Hence, the
fix in here eventually opted for emitting a non-public BPF_ST | BPF_NOSPEC
instruction which the x86 JIT translates into a lfence opcode. Inserting the
latter in between the store and load instruction is one of the mitigations
options [1]. The x86 instruction manual notes:

  [...] An LFENCE that follows an instruction that stores to memory might
  complete before the data being stored have become globally visible. [...]

The latter meaning that the preceding store instruction finished execution
and the store is at minimum guaranteed to be in the CPU's store queue, but
it's not guaranteed to be in that CPU's L1 cache at that point (globally
visible). The latter would only be guaranteed via sfence. So the load which
is guaranteed to execute after the lfence for that local CPU would have to
rely on store-to-load forwarding. [2], in section 2.3 on store buffers says:

  [...] For every store operation that is added to the ROB, an entry is
  allocated in the store buffer. This entry requires both the virtual and
  physical address of the target. Only if there is no free entry in the store
  buffer, the frontend stalls until there is an empty slot available in the
  store buffer again. Otherwise, the CPU can immediately continue adding
  subsequent instructions to the ROB and execute them out of order. On Intel
  CPUs, the store buffer has up to 56 entries. [...]

One small upside on the fix is that it lifts constraints from af86ca4e
where the sanitize_stack_off relative to r10 must be the same when coming
from different paths. The BPF_ST | BPF_NOSPEC gets emitted after a BPF_STX
or BPF_ST instruction. This happens either when we store a pointer or data
value to the BPF stack for the first time, or upon later pointer spills.
The former needs to be enforced since otherwise stale stack data could be
leaked under speculation as outlined earlier. For non-x86 JITs the BPF_ST |
BPF_NOSPEC mapping is currently optimized away, but others could emit a
speculation barrier as well if necessary. For real-world unprivileged
programs e.g. generated by LLVM, pointer spill/fill is only generated upon
register pressure and LLVM only tries to do that for pointers which are not
used often. The program main impact will be the initial BPF_ST | BPF_NOSPEC
sanitation for the STACK_INVALID case when the first write to a stack slot
occurs e.g. upon map lookup. In future we might refine ways to mitigate
the latter cost.

  [0] https://arxiv.org/pdf/1902.05178.pdf
  [1] https://msrc-blog.microsoft.com/2018/05/21/analysis-and-mitigation-of-speculative-store-bypass-cve-2018-3639/
  [2] https://arxiv.org/pdf/1905.05725.pdf

Fixes: af86ca4e ("bpf: Prevent memory disambiguation attack")
Fixes: f7cf25b2 ("bpf: track spill/fill of constants")
Co-developed-by: NPiotr Krysiuk <piotras@gmail.com>
Co-developed-by: NBenedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NPiotr Krysiuk <piotras@gmail.com>
Signed-off-by: NBenedict Schlueter <benedict.schlueter@rub.de>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
      2039f26f
    • D
      bpf: Introduce BPF nospec instruction for mitigating Spectre v4 · f5e81d11
      由 Daniel Borkmann 提交于 
      In case of JITs, each of the JIT backends compiles the BPF nospec instruction
/either/ to a machine instruction which emits a speculation barrier /or/ to
/no/ machine instruction in case the underlying architecture is not affected
by Speculative Store Bypass or has different mitigations in place already.

This covers both x86 and (implicitly) arm64: In case of x86, we use 'lfence'
instruction for mitigation. In case of arm64, we rely on the firmware mitigation
as controlled via the ssbd kernel parameter. Whenever the mitigation is enabled,
it works for all of the kernel code with no need to provide any additional
instructions here (hence only comment in arm64 JIT). Other archs can follow
as needed. The BPF nospec instruction is specifically targeting Spectre v4
since i) we don't use a serialization barrier for the Spectre v1 case, and
ii) mitigation instructions for v1 and v4 might be different on some archs.

The BPF nospec is required for a future commit, where the BPF verifier does
annotate intermediate BPF programs with speculation barriers.
Co-developed-by: NPiotr Krysiuk <piotras@gmail.com>
Co-developed-by: NBenedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NPiotr Krysiuk <piotras@gmail.com>
Signed-off-by: NBenedict Schlueter <benedict.schlueter@rub.de>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
      f5e81d11
    • T
      dmaengine: idxd: Change license on idxd.h to LGPL · 25905f60
      由 Tony Luck 提交于 
      This file was given GPL-2.0 license. But LGPL-2.1 makes more sense
as it needs to be used by libraries outside of the kernel source tree.
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      25905f60
  11. 28 7月, 2021 1 次提交
  13. 27 7月, 2021 2 次提交
    • D
      usb: otg-fsm: Fix hrtimer list corruption · bf88fef0
      由 Dmitry Osipenko 提交于 
      The HNP work can be re-scheduled while it's still in-fly. This results in
re-initialization of the busy work, resetting the hrtimer's list node of
the work and crashing kernel with null dereference within kernel/timer
once work's timer is expired. It's very easy to trigger this problem by
re-plugging USB cable quickly. Initialize HNP work only once to fix this
trouble.

 Unable to handle kernel NULL pointer dereference at virtual address 00000126)
 ...
 PC is at __run_timers.part.0+0x150/0x228
 LR is at __next_timer_interrupt+0x51/0x9c
 ...
 (__run_timers.part.0) from [<c0187a2b>] (run_timer_softirq+0x2f/0x50)
 (run_timer_softirq) from [<c01013ad>] (__do_softirq+0xd5/0x2f0)
 (__do_softirq) from [<c012589b>] (irq_exit+0xab/0xb8)
 (irq_exit) from [<c0170341>] (handle_domain_irq+0x45/0x60)
 (handle_domain_irq) from [<c04c4a43>] (gic_handle_irq+0x6b/0x7c)
 (gic_handle_irq) from [<c0100b65>] (__irq_svc+0x65/0xac)

Cc: stable@vger.kernel.org
Acked-by: NPeter Chen <peter.chen@kernel.org>
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20210717182134.30262-6-digetx@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bf88fef0
    • P
      net: llc: fix skb_over_panic · c7c9d210
      由 Pavel Skripkin 提交于 
      Syzbot reported skb_over_panic() in llc_pdu_init_as_xid_cmd(). The
problem was in wrong LCC header manipulations.

Syzbot's reproducer tries to send XID packet. llc_ui_sendmsg() is
doing following steps:

	1. skb allocation with size = len + header size
		len is passed from userpace and header size
		is 3 since addr->sllc_xid is set.

	2. skb_reserve() for header_len = 3
	3. filling all other space with memcpy_from_msg()

Ok, at this moment we have fully loaded skb, only headers needs to be
filled.

Then code comes to llc_sap_action_send_xid_c(). This function pushes 3
bytes for LLC PDU header and initializes it. Then comes
llc_pdu_init_as_xid_cmd(). It initalizes next 3 bytes *AFTER* LLC PDU
header and call skb_push(skb, 3). This looks wrong for 2 reasons:

	1. Bytes rigth after LLC header are user data, so this function
	   was overwriting payload.

	2. skb_push(skb, 3) call can cause skb_over_panic() since
	   all free space was filled in llc_ui_sendmsg(). (This can
	   happen is user passed 686 len: 686 + 14 (eth header) + 3 (LLC
	   header) = 703. SKB_DATA_ALIGN(703) = 704)

So, in this patch I added 2 new private constansts: LLC_PDU_TYPE_U_XID
and LLC_PDU_LEN_U_XID. LLC_PDU_LEN_U_XID is used to correctly reserve
header size to handle LLC + XID case. LLC_PDU_TYPE_U_XID is used by
llc_pdu_header_init() function to push 6 bytes instead of 3. And finally
I removed skb_push() call from llc_pdu_init_as_xid_cmd().

This changes should not affect other parts of LLC, since after
all steps we just transmit buffer.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+5e5a981ad7cc54c4b2b4@syzkaller.appspotmail.com
Signed-off-by: NPavel Skripkin <paskripkin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c7c9d210
  15. 26 7月, 2021 2 次提交
    • X
      sctp: send pmtu probe only if packet loss in Search Complete state · eacf078c
      由 Xin Long 提交于 
      This patch is to introduce last_rtx_chunks into sctp_transport to detect
if there's any packet retransmission/loss happened by checking against
asoc's rtx_data_chunks in sctp_transport_pl_send().

If there is, namely, transport->last_rtx_chunks != asoc->rtx_data_chunks,
the pmtu probe will be sent out. Otherwise, increment the pl.raise_count
and return when it's in Search Complete state.

With this patch, if in Search Complete state, which is a long period, it
doesn't need to keep probing the current pmtu unless there's data packet
loss. This will save quite some traffic.

v1->v2:
  - add the missing Fixes tag.

Fixes: 0dac127c ("sctp: do black hole detection in search complete state")
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      eacf078c
    • X
      sctp: improve the code for pmtu probe send and recv update · 058e6e0e
      由 Xin Long 提交于 
      This patch does 3 things:

  - make sctp_transport_pl_send() and sctp_transport_pl_recv()
    return bool type to decide if more probe is needed to send.

  - pr_debug() only when probe is really needed to send.

  - count pl.raise_count in sctp_transport_pl_send() instead of
    sctp_transport_pl_recv(), and it's only incremented for the
    1st probe for the same size.

These are preparations for the next patch to make probes happen
only when there's packet loss in Search Complete state.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      058e6e0e
  17. 25 7月, 2021 1 次提交
  19. 24 7月, 2021 3 次提交
  21. 22 7月, 2021 1 次提交
    • P
      cgroup1: fix leaked context root causing sporadic NULL deref in LTP · 1e7107c5
      由 Paul Gortmaker 提交于 
      Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests.  Things like:

   BUG: kernel NULL pointer dereference, address: 0000000000000008
   #PF: supervisor read access in kernel mode
   #PF: error_code(0x0000) - not-present page
   PGD 0 P4D 0
   Oops: 0000 [#1] PREEMPT SMP PTI
   CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1
   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
   RIP: 0010:kernfs_sop_show_path+0x1b/0x60

...or these others:

   RIP: 0010:do_mkdirat+0x6a/0xf0
   RIP: 0010:d_alloc_parallel+0x98/0x510
   RIP: 0010:do_readlinkat+0x86/0x120

There were other less common instances of some kind of a general scribble
but the common theme was mount and cgroup and a dubious dentry triggering
the NULL dereference.  I was only able to reproduce it under qemu by
replicating Richard's setup as closely as possible - I never did get it
to happen on bare metal, even while keeping everything else the same.

In commit 71d883c3 ("cgroup_do_mount(): massage calling conventions")
we see this as a part of the overall change:

   --------------
           struct cgroup_subsys *ss;
   -       struct dentry *dentry;

   [...]

   -       dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root,
   -                                CGROUP_SUPER_MAGIC, ns);

   [...]

   -       if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
   -               struct super_block *sb = dentry->d_sb;
   -               dput(dentry);
   +       ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
   +       if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
   +               struct super_block *sb = fc->root->d_sb;
   +               dput(fc->root);
                   deactivate_locked_super(sb);
                   msleep(10);
                   return restart_syscall();
           }
   --------------

In changing from the local "*dentry" variable to using fc->root, we now
export/leave that dentry pointer in the file context after doing the dput()
in the unlikely "is_dying" case.   With LTP doing a crazy amount of back to
back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely
becomes slightly likely and then bad things happen.

A fix would be to not leave the stale reference in fc->root as follows:

   --------------
                  dput(fc->root);
  +               fc->root = NULL;
                  deactivate_locked_super(sb);
   --------------

...but then we are just open-coding a duplicate of fc_drop_locked() so we
simply use that instead.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: stable@vger.kernel.org      # v5.1+
Reported-by: NRichard Purdie <richard.purdie@linuxfoundation.org>
Fixes: 71d883c3 ("cgroup_do_mount(): massage calling conventions")
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
      1e7107c5
  23. 21 7月, 2021 5 次提交
  25. 20 7月, 2021 3 次提交
    • C
      drm: Return -ENOTTY for non-drm ioctls · 3abab27c
      由 Charles Baylis 提交于 
      drm: Return -ENOTTY for non-drm ioctls

Return -ENOTTY from drm_ioctl() when userspace passes in a cmd number
which doesn't relate to the drm subsystem.

Glibc uses the TCGETS ioctl to implement isatty(), and without this
change isatty() returns it incorrectly returns true for drm devices.

To test run this command:
$ if [ -t 0 ]; then echo is a tty; fi < /dev/dri/card0
which shows "is a tty" without this patch.

This may also modify memory which the userspace application is not
expecting.
Signed-off-by: NCharles Baylis <cb-kernel@fishzet.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/YPG3IBlzaMhfPqCr@stando.fishzet.co.uk
      3abab27c
    • E
      net/tcp_fastopen: remove obsolete extern · 74946876
      由 Eric Dumazet 提交于 
      After cited commit, sysctl_tcp_fastopen_blackhole_timeout is no longer
a global variable.

Fixes: 3733be14 ("ipv4: Namespaceify tcp_fastopen_blackhole_timeout knob")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: NWei Wang <weiwan@google.com>
Link: https://lore.kernel.org/r/20210719092028.3016745-1-eric.dumazet@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
      74946876
    • L
      bpf: Fix OOB read when printing XDP link fdinfo · d6371c76
      由 Lorenz Bauer 提交于 
      We got the following UBSAN report on one of our testing machines:

    ================================================================================
    UBSAN: array-index-out-of-bounds in kernel/bpf/syscall.c:2389:24
    index 6 is out of range for type 'char *[6]'
    CPU: 43 PID: 930921 Comm: systemd-coredum Tainted: G           O      5.10.48-cloudflare-kasan-2021.7.0 #1
    Hardware name: <snip>
    Call Trace:
     dump_stack+0x7d/0xa3
     ubsan_epilogue+0x5/0x40
     __ubsan_handle_out_of_bounds.cold+0x43/0x48
     ? seq_printf+0x17d/0x250
     bpf_link_show_fdinfo+0x329/0x380
     ? bpf_map_value_size+0xe0/0xe0
     ? put_files_struct+0x20/0x2d0
     ? __kasan_kmalloc.constprop.0+0xc2/0xd0
     seq_show+0x3f7/0x540
     seq_read_iter+0x3f8/0x1040
     seq_read+0x329/0x500
     ? seq_read_iter+0x1040/0x1040
     ? __fsnotify_parent+0x80/0x820
     ? __fsnotify_update_child_dentry_flags+0x380/0x380
     vfs_read+0x123/0x460
     ksys_read+0xed/0x1c0
     ? __x64_sys_pwrite64+0x1f0/0x1f0
     do_syscall_64+0x33/0x40
     entry_SYSCALL_64_after_hwframe+0x44/0xa9
    <snip>
    ================================================================================
    ================================================================================
    UBSAN: object-size-mismatch in kernel/bpf/syscall.c:2384:2

From the report, we can infer that some array access in bpf_link_show_fdinfo at index 6
is out of bounds. The obvious candidate is bpf_link_type_strs[BPF_LINK_TYPE_XDP] with
BPF_LINK_TYPE_XDP == 6. It turns out that BPF_LINK_TYPE_XDP is missing from bpf_types.h
and therefore doesn't have an entry in bpf_link_type_strs:

    pos:	0
    flags:	02000000
    mnt_id:	13
    link_type:	(null)
    link_id:	4
    prog_tag:	bcf7977d3b93787c
    prog_id:	4
    ifindex:	1

Fixes: aa8d3a71 ("bpf, xdp: Add bpf_link-based XDP attachment API")
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210719085134.43325-2-lmb@cloudflare.com
      d6371c76
  27. 19 7月, 2021 1 次提交
  29. 18 7月, 2021 1 次提交
  31. 16 7月, 2021 8 次提交
  33. 15 7月, 2021 1 次提交