• Y
    bpf: fix sock hashmap kmalloc warning · 683d2ac3
    Yonghong Song 提交于
    syzbot reported a kernel warning below:
      WARNING: CPU: 0 PID: 4499 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
      Kernel panic - not syncing: panic_on_warn set ...
    
      CPU: 0 PID: 4499 Comm: syz-executor050 Not tainted 4.17.0-rc3+ #9
      Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
      Call Trace:
       __dump_stack lib/dump_stack.c:77 [inline]
       dump_stack+0x1b9/0x294 lib/dump_stack.c:113
       panic+0x22f/0x4de kernel/panic.c:184
       __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
       report_bug+0x252/0x2d0 lib/bug.c:186
       fixup_bug arch/x86/kernel/traps.c:178 [inline]
       do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
       do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
       invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
      RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:996
      RSP: 0018:ffff8801d907fc58 EFLAGS: 00010246
      RAX: 0000000000000000 RBX: ffff8801aeecb280 RCX: ffffffff8185ebd7
      RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000ffffffe1
      RBP: ffff8801d907fc58 R08: ffff8801adb5e1c0 R09: ffffed0035a84700
      R10: ffffed0035a84700 R11: ffff8801ad423803 R12: ffff8801aeecb280
      R13: 00000000fffffff4 R14: ffff8801ad891a00 R15: 00000000014200c0
       __do_kmalloc mm/slab.c:3713 [inline]
       __kmalloc+0x25/0x760 mm/slab.c:3727
       kmalloc include/linux/slab.h:517 [inline]
       map_get_next_key+0x24a/0x640 kernel/bpf/syscall.c:858
       __do_sys_bpf kernel/bpf/syscall.c:2131 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:2096 [inline]
       __x64_sys_bpf+0x354/0x4f0 kernel/bpf/syscall.c:2096
       do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    The test case is against sock hashmap with a key size 0xffffffe1.
    Such a large key size will cause the below code in function
    sock_hash_alloc() overflowing and produces a smaller elem_size,
    hence map creation will be successful.
        htab->elem_size = sizeof(struct htab_elem) +
                          round_up(htab->map.key_size, 8);
    
    Later, when map_get_next_key is called and kernel tries
    to allocate the key unsuccessfully, it will issue
    the above warning.
    
    Similar to hashtab, ensure the key size is at most
    MAX_BPF_STACK for a successful map creation.
    
    Fixes: 81110384 ("bpf: sockmap, add hash map support")
    Reported-by: syzbot+e4566d29080e7f3460ff@syzkaller.appspotmail.com
    Signed-off-by: NYonghong Song <yhs@fb.com>
    Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
    Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
    683d2ac3
sockmap.c 56.3 KB