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| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-24 09:19:25 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-04-24 12:19:45 +0200 |
| commit | 29da93fea3ea39ab9b12270cc6be1b70ef201c9e (patch) | |
| tree | 1d5dd50a2abb3145a22d6a398cafad8f9067de90 /lib/strncpy_from_user.c | |
| parent | 6ae865615fc43d014da2fd1f1bba7e81ee622d1b (diff) | |
| download | linux-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.c | 5 |
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 |