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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2018-02-01 21:00:50 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-01 12:20:21 -0800
commit1a3241ff10d038ecd096d03380327f2a0b5840a6 (patch)
tree0a0529936bc1255b927021cd4a0a3f2cd025c3f7
parent7f1e541fc8d57a143dd5df1d0a1276046e08c083 (diff)
lib/strscpy: Shut up KASAN false-positives in strscpy()
strscpy() performs the word-at-a-time optimistic reads. So it may may access the memory past the end of the object, which is perfectly fine since strscpy() doesn't use that (past-the-end) data and makes sure the optimistic read won't cross a page boundary. Use new read_word_at_a_time() to shut up the KASAN. Note that this potentially could hide some bugs. In example bellow, stscpy() will copy more than we should (1-3 extra uninitialized bytes): char dst[8]; char *src; src = kmalloc(5, GFP_KERNEL); memset(src, 0xff, 5); strscpy(dst, src, 8); Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/string.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/string.c b/lib/string.c
index 64a9e33f1daa..2c0900a5d51a 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -203,7 +203,7 @@ ssize_t strscpy(char *dest, const char *src, size_t count)
while (max >= sizeof(unsigned long)) {
unsigned long c, data;
- c = *(unsigned long *)(src+res);
+ c = read_word_at_a_time(src+res);
if (has_zero(c, &data, &constants)) {
data = prep_zero_mask(c, data, &constants);
data = create_zero_mask(data);