Hi, all. Recently syzbot reported a bug as following: kernel BUG at fs/f2fs/inode.c:896! CPU: 1 UID: 0 PID: 5217 Comm: syz-executor605 Not tainted 6.11.0-rc4-syzkaller-00033-g872cf28b8df9 #0 RIP: 0010:f2fs_evict_inode+0x1598/0x15c0 fs/f2fs/inode.c:896 Call Trace: <TASK> evict+0x532/0x950 fs/inode.c:704 dispose_list fs/inode.c:747 [inline] evict_inodes+0x5f9/0x690 fs/inode.c:797 generic_shutdown_super+0x9d/0x2d0 fs/super.c:627 kill_block_super+0x44/0x90 fs/super.c:1696 kill_f2fs_super+0x344/0x690 fs/f2fs/super.c:4898 deactivate_locked_super+0xc4/0x130 fs/super.c:473 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373 task_work_run+0x24f/0x310 kernel/task_work.c:228 ptrace_notify+0x2d2/0x380 kernel/signal.c:2402 ptrace_report_syscall include/linux/ptrace.h:415 [inline] ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline] syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline] syscall_exit_to_user_mode+0x279/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f The syzbot constructed the following scenario: concurrently creating directories and setting the file system to read-only. In this case, while f2fs was making dir, the filesystem switched to readonly, and when it tried to clear the dirty flag, it triggered this code path: f2fs_mkdir()-> f2fs_sync_fs()->f2fs_write_checkpoint() ->f2fs_readonly(). This resulted FI_DIRTY_INODE flag not being cleared, which eventually led to a bug being triggered during the FI_DIRTY_INODE check in f2fs_evict_inode(). In this case, we cannot do anything further, so if filesystem is readonly, do not trigger the BUG. Instead, clean up resources to the best of our ability to prevent triggering subsequent resource leak checks. If there is anything important I'm missing, please let me know, thanks. Reported-by: syzbot+ebea2790904673d7c618@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=ebea2790904673d7c618 Fixes: ca7d802a7d8e ("f2fs: detect dirty inode in evict_inode") CC: stable@xxxxxxxxxxxxxxx Signed-off-by: Julian Sun <sunjunchao2870@xxxxxxxxx> --- fs/f2fs/inode.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index aef57172014f..52d273383ec2 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -892,8 +892,12 @@ void f2fs_evict_inode(struct inode *inode) atomic_read(&fi->i_compr_blocks)); if (likely(!f2fs_cp_error(sbi) && - !is_sbi_flag_set(sbi, SBI_CP_DISABLED))) - f2fs_bug_on(sbi, is_inode_flag_set(inode, FI_DIRTY_INODE)); + !is_sbi_flag_set(sbi, SBI_CP_DISABLED))) { + if (!f2fs_readonly(sbi->sb)) + f2fs_bug_on(sbi, is_inode_flag_set(inode, FI_DIRTY_INODE)); + else + f2fs_inode_synced(inode); + } else f2fs_inode_synced(inode); -- 2.39.2
