[PATCH AUTOSEL 4.19 05/37] f2fs: fix to do sanity check on valid node/block count

Sasha Levin
2019-10-25T13:56:17Z

From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 7b63f72f73af57bb040f03b9713ec9979d8911f4 ]

As Jungyeon reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=203229

- 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

- Kernel message
kernel BUG at fs/f2fs/recovery.c:591!
RIP: 0010:recover_data+0x12d8/0x1780
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

With corrupted image wihch has out-of-range valid node/block count, during
recovery, once we failed due to no free space, it will trigger kernel
panic.

Adding sanity check on valid node/block count in f2fs_sanity_check_ckpt()
to detect such condition, so that potential panic can be avoided.

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/super.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 6851afc3bf805..3fc96cffe6ac5 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2344,7 +2344,8 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
unsigned int log_blocks_per_seg;
unsigned int segment_count_main;
unsigned int cp_pack_start_sum, cp_payload;
- block_t user_block_count;
+ block_t user_block_count, valid_user_blocks;
+ block_t avail_node_count, valid_node_count;
int i, j;

total = le32_to_cpu(raw_super->segment_count);
@@ -2379,6 +2380,24 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
return 1;
}

+ valid_user_blocks = le64_to_cpu(ckpt->valid_block_count);
+ if (valid_user_blocks > user_block_count) {
+ f2fs_msg(sbi->sb, KERN_ERR,
+ "Wrong valid_user_blocks: %u, user_block_count: %u",
+ valid_user_blocks, user_block_count);
+ return 1;
+ }
+
+ valid_node_count = le32_to_cpu(ckpt->valid_node_count);
+ avail_node_count = sbi->total_node_count - sbi->nquota_files -
+ F2FS_RESERVED_NODE_NUM;
+ if (valid_node_count > avail_node_count) {
+ f2fs_msg(sbi->sb, KERN_ERR,
+ "Wrong valid_node_count: %u, avail_node_count: %u",
+ valid_node_count, avail_node_count);
+ return 1;
+ }
+
main_segs = le32_to_cpu(raw_super->segment_count_main);
blocks_per_seg = sbi->blocks_per_seg;

--
2.20.1