[PATCH AUTOSEL 5.1 043/186] f2fs: fix to avoid panic in do_recover_data()

Sasha Levin
2019-06-01T13:42:54Z

From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 22d61e286e2d9097dae36f75ed48801056b77cac ]

As Jungyeon reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=203227

- Overview
When mounting the attached crafted image, following errors are reported.
Additionally, it hangs on sync after trying to mount it.

The image is intentionally fuzzed from a normal f2fs image for testing.
Compile options for F2FS are as follows.
CONFIG_F2FS_FS=y
CONFIG_F2FS_STAT_FS=y
CONFIG_F2FS_FS_XATTR=y
CONFIG_F2FS_FS_POSIX_ACL=y
CONFIG_F2FS_CHECK_FS=y

- Reproduces
mkdir test
mount -t f2fs tmp.img test
sync

- Messages
kernel BUG at fs/f2fs/recovery.c:549!
RIP: 0010:recover_data+0x167a/0x1780
Call Trace:
f2fs_recover_fsync_data+0x613/0x710
f2fs_fill_super+0x1043/0x1aa0
mount_bdev+0x16d/0x1a0
mount_fs+0x4a/0x170
vfs_kern_mount+0x5d/0x100
do_mount+0x200/0xcf0
ksys_mount+0x79/0xc0
__x64_sys_mount+0x1c/0x20
do_syscall_64+0x43/0xf0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

During recovery, if ofs_of_node is inconsistent in between recovered
node page and original checkpointed node page, let's just fail recovery
instead of making kernel panic.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/recovery.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index e3883db868d81..73338c432e7e4 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -546,7 +546,15 @@ static int do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
goto err;

f2fs_bug_on(sbi, ni.ino != ino_of_node(page));
- f2fs_bug_on(sbi, ofs_of_node(dn.node_page) != ofs_of_node(page));
+
+ if (ofs_of_node(dn.node_page) != ofs_of_node(page)) {
+ f2fs_msg(sbi->sb, KERN_WARNING,
+ "Inconsistent ofs_of_node, ino:%lu, ofs:%u, %u",
+ inode->i_ino, ofs_of_node(dn.node_page),
+ ofs_of_node(page));
+ err = -EFAULT;
+ goto err;
+ }

for (; start < end; start++, dn.ofs_in_node++) {
block_t src, dest;
--
2.20.1