From: Gao Xiang hsiangkao@linux.alibaba.com
[ Upstream commit dcbe6803fffd387f72b48c2373b5f5ed12a5804b ]
I got some KASAN report as below:
[ 46.959738] ================================================================== [ 46.960430] BUG: KASAN: use-after-free in z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188 ... [ 46.960430] Call Trace: [ 46.960430] <TASK> [ 46.960430] dump_stack_lvl+0x41/0x5e [ 46.960430] print_report.cold+0xb2/0x6b7 [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] kasan_report+0x8a/0x140 [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] kasan_check_range+0x14d/0x1d0 [ 46.960430] memcpy+0x20/0x60 [ 46.960430] z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] z_erofs_decompress_pcluster+0xaae/0x1080
The root cause is that the tail pcluster won't be a complete filesystem block anymore. So if ztailpacking is used, the second part of an uncompressed tail pcluster may not be ``rq->pageofs_out``.
Fixes: ab749badf9f4 ("erofs: support unaligned data decompression") Fixes: cecf864d3d76 ("erofs: support inline data decompression") Reviewed-by: Yue Hu huyue2@coolpad.com Reviewed-by: Chao Yu chao@kernel.org Link: https://lore.kernel.org/r/20220512115833.24175-1-hsiangkao@linux.alibaba.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/decompressor.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 3efa686c7644..0e0d1fc0f130 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -322,6 +322,7 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; const unsigned int righthalf = min_t(unsigned int, rq->outputsize, PAGE_SIZE - rq->pageofs_out); + const unsigned int lefthalf = rq->outputsize - righthalf; unsigned char *src, *dst;
if (nrpages_out > 2) { @@ -344,10 +345,10 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, if (nrpages_out == 2) { DBG_BUGON(!rq->out[1]); if (rq->out[1] == *rq->in) { - memmove(src, src + righthalf, rq->pageofs_out); + memmove(src, src + righthalf, lefthalf); } else { dst = kmap_atomic(rq->out[1]); - memcpy(dst, src + righthalf, rq->pageofs_out); + memcpy(dst, src + righthalf, lefthalf); kunmap_atomic(dst); } }