From: KP Singh <kpsingh@xxxxxxxxxxxx> Subject: lib: Add might_fault() to strncpy_from_user. From: KP Singh <kpsingh@xxxxxxxxxx> 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@xxxxxxxxxxxx Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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; _
