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authorPeter Zijlstra <peterz@infradead.org>2019-04-24 09:19:25 +0200
committerIngo Molnar <mingo@kernel.org>2019-04-24 12:19:45 +0200
commit29da93fea3ea39ab9b12270cc6be1b70ef201c9e (patch)
tree1d5dd50a2abb3145a22d6a398cafad8f9067de90 /lib/strncpy_from_user.c
parent6ae865615fc43d014da2fd1f1bba7e81ee622d1b (diff)
downloadlinux-29da93fea3ea39ab9b12270cc6be1b70ef201c9e.tar.bz2
mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
Randy reported objtool triggered on his (GCC-7.4) build: lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x315: call to __ubsan_handle_add_overflow() with UACCESS enabled lib/strnlen_user.o: warning: objtool: strnlen_user()+0x337: call to __ubsan_handle_sub_overflow() with UACCESS enabled This is due to UBSAN generating signed-overflow-UB warnings where it should not. Prior to GCC-8 UBSAN ignored -fwrapv (which the kernel uses through -fno-strict-overflow). Make the functions use 'unsigned long' throughout. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: luto@kernel.org Link: http://lkml.kernel.org/r/20190424072208.754094071@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib/strncpy_from_user.c')
-rw-r--r--lib/strncpy_from_user.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 58eacd41526c..023ba9f3b99f 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -23,10 +23,11 @@
* hit it), 'max' is the address space maximum (and we return
* -EFAULT if we hit it).
*/
-static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
+static inline long do_strncpy_from_user(char *dst, const char __user *src,
+ unsigned long count, unsigned long max)
{
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
- long res = 0;
+ unsigned long res = 0;
/*
* Truncate 'max' to the user-specified limit, so that