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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>
This commit is contained in:
KP Singh 2020-06-04 16:50:11 -07:00 committed by Linus Torvalds
parent 9ac1757580
commit 0788735899
1 changed files with 1 additions and 0 deletions
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lib/strncpy_from_user.c
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@ -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;