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authorGuo Xuenan <guoxuenan@huawei.com>2022-04-08 23:08:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-09 03:20:36 +0300
commiteafc0a02391b7b36617b36c97c4b5d6832cf5e24 (patch)
tree7424b85c0801a6baf663935aea9554fc23ad7234 /lib/lz4
parent66f133ceab7456c789f70a242991ed1b27ba1c3d (diff)
downloadlinux-eafc0a02391b7b36617b36c97c4b5d6832cf5e24.tar.xz
lz4: fix LZ4_decompress_safe_partial read out of bound
When partialDecoding, it is EOF if we've either filled the output buffer or can't proceed with reading an offset for following match. In some extreme corner cases when compressed data is suitably corrupted, UAF will occur. As reported by KASAN [1], LZ4_decompress_safe_partial may lead to read out of bound problem during decoding. lz4 upstream has fixed it [2] and this issue has been disscussed here [3] before. current decompression routine was ported from lz4 v1.8.3, bumping lib/lz4 to v1.9.+ is certainly a huge work to be done later, so, we'd better fix it first. [1] https://lore.kernel.org/all/000000000000830d1205cf7f0477@google.com/ [2] https://github.com/lz4/lz4/commit/c5d6f8a8be3927c0bec91bcc58667a6cfad244ad# [3] https://lore.kernel.org/all/CC666AE8-4CA4-4951-B6FB-A2EFDE3AC03B@fb.com/ Link: https://lkml.kernel.org/r/20211111105048.2006070-1-guoxuenan@huawei.com Reported-by: syzbot+63d688f1d899c588fb71@syzkaller.appspotmail.com Signed-off-by: Guo Xuenan <guoxuenan@huawei.com> Reviewed-by: Nick Terrell <terrelln@fb.com> Acked-by: Gao Xiang <hsiangkao@linux.alibaba.com> Cc: Yann Collet <cyan@fb.com> Cc: Chengyang Fan <cy.fan@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/lz4')
-rw-r--r--lib/lz4/lz4_decompress.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index 926f4823d5ea..fd1728d94bab 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -271,8 +271,12 @@ static FORCE_INLINE int LZ4_decompress_generic(
ip += length;
op += length;
- /* Necessarily EOF, due to parsing restrictions */
- if (!partialDecoding || (cpy == oend))
+ /* Necessarily EOF when !partialDecoding.
+ * When partialDecoding, it is EOF if we've either
+ * filled the output buffer or
+ * can't proceed with reading an offset for following match.
+ */
+ if (!partialDecoding || (cpy == oend) || (ip >= (iend - 2)))
break;
} else {
/* may overwrite up to WILDCOPYLENGTH beyond cpy */