diff options
| author | Gao Xiang <gaoxiang25@huawei.com> | 2020-01-07 05:25:46 +0300 |
|---|---|---|
| committer | Gao Xiang <gaoxiang25@huawei.com> | 2020-01-11 13:29:19 +0300 |
| commit | 4d2024370d877f9ac8b98694bcff666da6a5d333 (patch) | |
| tree | 33e0647654abdca047ab3584abc4a0b26378c84d /fs/erofs/decompressor.c | |
| parent | e3915ad94bfa0e2c1818837af618e9adec74eb1b (diff) | |
| download | linux-4d2024370d877f9ac8b98694bcff666da6a5d333.tar.xz | |
erofs: fix out-of-bound read for shifted uncompressed block
rq->out[1] should be valid before accessing. Otherwise,
in very rare cases, out-of-bound dirty onstack rq->out[1]
can equal to *in and lead to unintended memmove behavior.
Link: https://lore.kernel.org/r/20200107022546.19432-1-gaoxiang25@huawei.com
Fixes: 7fc45dbc938a ("staging: erofs: introduce generic decompression backend")
Cc: <stable@vger.kernel.org> # 5.3+
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Diffstat (limited to 'fs/erofs/decompressor.c')
| -rw-r--r-- | fs/erofs/decompressor.c | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 2890a67a1ded..5779a15c2cd6 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -306,24 +306,22 @@ static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq, } src = kmap_atomic(*rq->in); - if (!rq->out[0]) { - dst = NULL; - } else { + if (rq->out[0]) { dst = kmap_atomic(rq->out[0]); memcpy(dst + rq->pageofs_out, src, righthalf); + kunmap_atomic(dst); } - if (rq->out[1] == *rq->in) { - memmove(src, src + righthalf, rq->pageofs_out); - } else if (nrpages_out == 2) { - if (dst) - kunmap_atomic(dst); + if (nrpages_out == 2) { DBG_BUGON(!rq->out[1]); - dst = kmap_atomic(rq->out[1]); - memcpy(dst, src + righthalf, rq->pageofs_out); + if (rq->out[1] == *rq->in) { + memmove(src, src + righthalf, rq->pageofs_out); + } else { + dst = kmap_atomic(rq->out[1]); + memcpy(dst, src + righthalf, rq->pageofs_out); + kunmap_atomic(dst); + } } - if (dst) - kunmap_atomic(dst); kunmap_atomic(src); return 0; } |