Commit 07887358 authored Jun 04, 2020 by KP Singh Committed by Linus Torvalds Jun 04, 2020

lib: Add might_fault() to strncpy_from_user.



When updating a piece of broken logic from using get_user to
strncpy_from_user, we noticed that a warning which is expected when
calling a function that might fault from an atomic context with
pagefaults enabled disappeared.

Not having this warning in place can lead to calling strncpy_from_user
from an atomic context and eventually kernel crashes/stack corruption.

Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20200414225705.255711-1-kpsingh@chromium.org


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 9ac17575

lib/strncpy_from_user.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -98,6 +98,7 @@ long strncpy_from_user(char dst, const char __user src, long count)
		{
		unsigned long max_addr, src_addr;

		might_fault();
		if (unlikely(count <= 0))
		return 0;

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