+ lib-add-might_fault-to-strncpy_from_user.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: lib: Add might_fault() to strncpy_from_user.
has been added to the -mm tree.  Its filename is
     lib-add-might_fault-to-strncpy_from_user.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/lib-add-might_fault-to-strncpy_from_user.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/lib-add-might_fault-to-strncpy_from_user.patch

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------------------------------------------------------
From: KP Singh <kpsingh@chromium.org>
Subject: 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.

Link: http://lkml.kernel.org/r/20200414225705.255711-1-kpsingh@chromium.org
Signed-off-by: KP Singh <kpsingh@google.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/strncpy_from_user.c |    1 +
 1 file changed, 1 insertion(+)

--- a/lib/strncpy_from_user.c~lib-add-might_fault-to-strncpy_from_user
+++ a/lib/strncpy_from_user.c
@@ -98,6 +98,7 @@ long strncpy_from_user(char *dst, const
 {
 	unsigned long max_addr, src_addr;
 
+	might_fault();
 	if (unlikely(count <= 0))
 		return 0;
 
_

Patches currently in -mm which might be from kpsingh@chromium.org are

lib-add-might_fault-to-strncpy_from_user.patch