From: Gao Xiang hsiangkao@linux.alibaba.com
[ 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@google.com
Reported-and-tested-by: syzbot+aafb3f37cfeb6534c4ac@syzkaller.appspotmail.com Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter") Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support") Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Reviewed-by: Chao Yu chao@kernel.org Link: https://lore.kernel.org/r/20230410173714.104604-1-hsiangkao@linux.alibaba.co... Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/zmap.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 655da4d739cb6..b5f4086537548 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -86,6 +86,10 @@ 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: