From: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> [ Upstream commit cc4efd3dd2ac9f89143e5d881609747ecff04164 ] Syzbot generated a crafted image [1] with a non-compact HEAD index of clusterofs 33024 while valid numbers should be 0 ~ lclustersize-1, which causes the following unexpected behavior as below: BUG: unable to handle page fault for address: fffff52101a3fff9 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 23ffed067 P4D 23ffed067 PUD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 4398 Comm: kworker/u5:1 Not tainted 6.3.0-rc6-syzkaller-g09a9639e56c0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Workqueue: erofs_worker z_erofs_decompressqueue_work RIP: 0010:z_erofs_decompress_queue+0xb7e/0x2b40 ... Call Trace: <TASK> z_erofs_decompressqueue_work+0x99/0xe0 process_one_work+0x8f6/0x1170 worker_thread+0xa63/0x1210 kthread+0x270/0x300 ret_from_fork+0x1f/0x30 Note that normal images or images using compact indexes are not impacted. Let's fix this now. [1] https://lore.kernel.org/r/000000000000ec75b005ee97fbaa@xxxxxxxxxx Reported-and-tested-by: syzbot+aafb3f37cfeb6534c4ac@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter") Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support") Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> Reviewed-by: Chao Yu <chao@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230410173714.104604-1-hsiangkao@xxxxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/erofs/zmap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 98fb90b9af715..91733f8ecdffc 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -211,6 +211,10 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m, if (advise & Z_EROFS_VLE_DI_PARTIAL_REF) m->partialref = true; m->clusterofs = le16_to_cpu(di->di_clusterofs); + if (m->clusterofs >= 1 << vi->z_logical_clusterbits) { + DBG_BUGON(1); + return -EFSCORRUPTED; + } m->pblk = le32_to_cpu(di->di_u.blkaddr); break; default: -- 2.39.2
