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| author | Mikulas Patocka <mpatocka@redhat.com> | 2022-04-19 16:56:23 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-04-20 21:38:49 +0300 |
| commit | a6823e4e360fe975bd3da4ab156df7c74c8b07f3 (patch) | |
| tree | 0fdd5dfb998a6ca316ba4bcb7d89e94044ce29be /arch/x86/lib | |
| parent | 559089e0a93d44280ec3ab478830af319c56dbe3 (diff) | |
| download | linux-a6823e4e360fe975bd3da4ab156df7c74c8b07f3.tar.xz | |
x86: __memcpy_flushcache: fix wrong alignment if size > 2^32
The first "if" condition in __memcpy_flushcache is supposed to align the
"dest" variable to 8 bytes and copy data up to this alignment. However,
this condition may misbehave if "size" is greater than 4GiB.
The statement min_t(unsigned, size, ALIGN(dest, 8) - dest); casts both
arguments to unsigned int and selects the smaller one. However, the
cast truncates high bits in "size" and it results in misbehavior.
For example:
suppose that size == 0x100000001, dest == 0x200000002
min_t(unsigned, size, ALIGN(dest, 8) - dest) == min_t(0x1, 0xe) == 0x1;
...
dest += 0x1;
so we copy just one byte "and" dest remains unaligned.
This patch fixes the bug by replacing unsigned with size_t.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/usercopy_64.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 0402a749f3a0..0ae6cf804197 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -119,7 +119,7 @@ void __memcpy_flushcache(void *_dst, const void *_src, size_t size) /* cache copy and flush to align dest */ if (!IS_ALIGNED(dest, 8)) { - unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest); + size_t len = min_t(size_t, size, ALIGN(dest, 8) - dest); memcpy((void *) dest, (void *) source, len); clean_cache_range((void *) dest, len); |