* [PATCH] lib: Add might_fault() to strncpy_from_user.
@ 2020-04-14 22:57 KP Singh
0 siblings, 0 replies; only message in thread
From: KP Singh @ 2020-04-14 22:57 UTC (permalink / raw)
To: linux-kernel; +Cc: Jann Horn, Christophe Leroy, Peter Zijlstra, Andrew Morton
From: KP Singh <kpsingh@google.com>
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.
Cc: Jann Horn <jannh@google.com>
Signed-off-by: KP Singh <kpsingh@google.com>
---
lib/strncpy_from_user.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 706020b06617..16e78d0bb5d4 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -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;
--
2.26.0.110.g2183baf09c-goog
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