stable inclusion
from stable-v5.10.170
commit 3b6ce54cfa2c04f0636fd0c985913af8703b408d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I71N8L
CVE: CVE-2023-0459

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3b6ce54cfa2c04f0636fd0c985913af8703b408d

--------------------------------

commit 74e19ef0 upstream.

The results of "access_ok()" can be mis-speculated.  The result is that
you can end speculatively:

	if (access_ok(from, size))
		// Right here

even for bad from/size combinations.  On first glance, it would be ideal
to just add a speculation barrier to "access_ok()" so that its results
can never be mis-speculated.

But there are lots of system calls just doing access_ok() via
"copy_to_user()" and friends (example: fstat() and friends).  Those are
generally not problematic because they do not _consume_ data from
userspace other than the pointer.  They are also very quick and common
system calls that should not be needlessly slowed down.

"copy_from_user()" on the other hand uses a user-controller pointer and
is frequently followed up with code that might affect caches.  Take
something like this:

	if (!copy_from_user(&kernelvar, uptr, size))
		do_something_with(kernelvar);

If userspace passes in an evil 'uptr' that *actually* points to a kernel
addresses, and then do_something_with() has cache (or other)
side-effects, it could allow userspace to infer kernel data values.

Add a barrier to the common copy_from_user() code to prevent
mis-speculated values which happen after the copy.

Also add a stub for architectures that do not define barrier_nospec().
This makes the macro usable in generic code.

Since the barrier is now usable in generic code, the x86 #ifdef in the
BPF code can also go away.
Reported-by: NJordy Zomer <jordyzomer@google.com>
Suggested-by: NLinus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>   # BPF bits
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	lib/usercopy.c
Signed-off-by: NMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: NNanyong Sun <sunnanyong@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>