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erofs: validate the extent length for uncompressed pclusters

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syzkaller reported a KASAN use-after-free:
https://syzkaller.appspot.com/bug?extid=2ae90e873e97f1faf6f2

The referenced fuzzed image actually has two issues:
 - m_pa == 0 as a non-inlined pcluster;
 - The logical length is longer than its physical length.

The first issue has already been addressed.  This patch addresses
the second issue by checking the extent length validity.

Reported-by: syzbot+2ae90e873e97f1faf6f2@syzkaller.appspotmail.com
Fixes: 02827e1796 ("staging: erofs: add erofs_map_blocks_iter")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221205150050.47784-2-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang 2022-12-05 23:00:50 +08:00
parent d5d188b8f8
commit c505feba4c
1 changed files with 5 additions and 0 deletions
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5
fs/erofs/zmap.c
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@ -698,6 +698,11 @@ static int z_erofs_do_map_blocks(struct inode *inode,
}
if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN) {
if (map->m_llen > map->m_plen) {
DBG_BUGON(1);
err = -EFSCORRUPTED;
goto unmap_out;
}
if (vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER)
map->m_algorithmformat =
Z_EROFS_COMPRESSION_INTERLACED;