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Subject[PATCH AUTOSEL 4.14 29/99] f2fs: fix to avoid panic in dec_valid_block_count()
Date
From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 5e159cd349bf3a31fb7e35c23a93308eb30f4f71 ]

As Jungyeon reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=203209

- Overview
When mounting the attached crafted image and running program, I got this error.
Additionally, it hangs on sync after the this script.

The image is intentionally fuzzed from a normal f2fs image for testing and I enabled option CONFIG_F2FS_CHECK_FS on.

- Reproduces
cc poc_01.c
./run.sh f2fs
sync

kernel BUG at fs/f2fs/f2fs.h:1788!
RIP: 0010:f2fs_truncate_data_blocks_range+0x342/0x350
Call Trace:
f2fs_truncate_blocks+0x36d/0x3c0
f2fs_truncate+0x88/0x110
f2fs_setattr+0x3e1/0x460
notify_change+0x2da/0x400
do_truncate+0x6d/0xb0
do_sys_ftruncate+0xf1/0x160
do_syscall_64+0x43/0xf0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The reason is dec_valid_block_count() will trigger kernel panic due to
inconsistent count in between inode.i_blocks and actual block.

To avoid panic, let's just print debug message and set SBI_NEED_FSCK to
give a hint to fsck for latter repairing.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix build warning and add unlikely]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/f2fs.h | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 634165fb64f15..daa136ec3b1ec 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1539,6 +1539,7 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
return -ENOSPC;
}

+void f2fs_msg(struct super_block *sb, const char *level, const char *fmt, ...);
static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,
struct inode *inode,
block_t count)
@@ -1547,9 +1548,17 @@ static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,

spin_lock(&sbi->stat_lock);
f2fs_bug_on(sbi, sbi->total_valid_block_count < (block_t) count);
- f2fs_bug_on(sbi, inode->i_blocks < sectors);
sbi->total_valid_block_count -= (block_t)count;
spin_unlock(&sbi->stat_lock);
+ if (unlikely(inode->i_blocks < sectors)) {
+ f2fs_msg(sbi->sb, KERN_WARNING,
+ "Inconsistent i_blocks, ino:%lu, iblocks:%llu, sectors:%llu",
+ inode->i_ino,
+ (unsigned long long)inode->i_blocks,
+ (unsigned long long)sectors);
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ return;
+ }
f2fs_i_blocks_write(inode, count, false, true);
}

@@ -2371,7 +2380,6 @@ static inline void f2fs_update_iostat(struct f2fs_sb_info *sbi,

bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
block_t blkaddr, int type);
-void f2fs_msg(struct super_block *sb, const char *level, const char *fmt, ...);
static inline void verify_blkaddr(struct f2fs_sb_info *sbi,
block_t blkaddr, int type)
{
--
2.20.1
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