This is a note to let you know that I've just added the patch titled erofs: validate the extent length for uncompressed pclusters to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: erofs-validate-the-extent-length-for-uncompressed-pc.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit e28d9075ffb0486e3e0a8406b9033d34da6fc940 Author: Gao Xiang <xiang@xxxxxxxxxx> Date: Mon Dec 5 23:00:50 2022 +0800 erofs: validate the extent length for uncompressed pclusters [ Upstream commit c505feba4c0d76084e56ec498ce819f02a7043ae ] 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@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter") Reviewed-by: Chao Yu <chao@xxxxxxxxxx> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20221205150050.47784-2-hsiangkao@xxxxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index f49295b9f2e1..e6d5d7a18fb0 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;