From: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> [ 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> --- fs/erofs/zmap.c | 5 +++++ 1 file changed, 5 insertions(+) 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; -- 2.35.1
