diff mbox series

[2/2] erofs: validate the extent length for uncompressed pclusters

Message ID 20221205150050.47784-2-hsiangkao@linux.alibaba.com
State New
Headers
Series [1/2] erofs: fix missing unmap if z_erofs_get_extent_compressedlen() fails |

Commit Message

Gao Xiang Dec. 5, 2022, 3 p.m. UTC 
  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: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/zmap.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Chao Yu Dec. 6, 2022, 3:09 p.m. UTC | #1 
On 2022/12/5 23:00, Gao Xiang wrote:
> 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: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,
diff mbox series

Patch

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 98eff1259de4..0150570c33aa 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -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;