Re: [PATCH 3/3] f2fs: fix to do sanity check on i_nid for inline_data inode

Jaegeuk Kim
2024-05-09T15:53:00Z

On 05/06, Chao Yu wrote:
> syzbot reports a f2fs bug as below:
>
> ------------[ cut here ]------------
> kernel BUG at fs/f2fs/inline.c:258!
> CPU: 1 PID: 34 Comm: kworker/u8:2 Not tainted 6.9.0-rc6-syzkaller-00012-g9e4bc4bcae01 #0
> RIP: 0010:f2fs_write_inline_data+0x781/0x790 fs/f2fs/inline.c:258
> Call Trace:
> f2fs_write_single_data_page+0xb65/0x1d60 fs/f2fs/data.c:2834
> f2fs_write_cache_pages fs/f2fs/data.c:3133 [inline]
> __f2fs_write_data_pages fs/f2fs/data.c:3288 [inline]
> f2fs_write_data_pages+0x1efe/0x3a90 fs/f2fs/data.c:3315
> do_writepages+0x35b/0x870 mm/page-writeback.c:2612
> __writeback_single_inode+0x165/0x10b0 fs/fs-writeback.c:1650
> writeback_sb_inodes+0x905/0x1260 fs/fs-writeback.c:1941
> wb_writeback+0x457/0xce0 fs/fs-writeback.c:2117
> wb_do_writeback fs/fs-writeback.c:2264 [inline]
> wb_workfn+0x410/0x1090 fs/fs-writeback.c:2304
> process_one_work kernel/workqueue.c:3254 [inline]
> process_scheduled_works+0xa12/0x17c0 kernel/workqueue.c:3335
> worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
> kthread+0x2f2/0x390 kernel/kthread.c:388
> ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> The root cause is: inline_data inode can be fuzzed, so that there may
> be valid blkaddr in its direct node, once f2fs triggers background GC
> to migrate the block, it will hit f2fs_bug_on() during dirty page
> writeback.
>
> Let's add sanity check on i_nid field for inline_data inode, meanwhile,
> forbid to migrate inline_data inode's data block to fix this issue.
>
> Reported-by: syzbot+848062ba19c8782ca5c8@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/linux-f2fs-devel/000000000000d103ce06174d7ec3@google.com
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> fs/f2fs/f2fs.h | 2 +-
> fs/f2fs/gc.c | 6 ++++++
> fs/f2fs/inline.c | 17 ++++++++++++++++-
> fs/f2fs/inode.c | 2 +-
> 4 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index fced2b7652f4..c876813b5532 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4146,7 +4146,7 @@ extern struct kmem_cache *f2fs_inode_entry_slab;
> * inline.c
> */
> bool f2fs_may_inline_data(struct inode *inode);
> -bool f2fs_sanity_check_inline_data(struct inode *inode);
> +bool f2fs_sanity_check_inline_data(struct inode *inode, struct page *ipage);
> bool f2fs_may_inline_dentry(struct inode *inode);
> void f2fs_do_read_inline_data(struct page *page, struct page *ipage);
> void f2fs_truncate_inline_inode(struct inode *inode,
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index e86c7f01539a..041957750478 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1563,6 +1563,12 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> continue;
> }
>
> + if (f2fs_has_inline_data(inode)) {
> + iput(inode);
> + set_sbi_flag(sbi, SBI_NEED_FSCK);
> + continue;

Any race condtion to get this as false alarm?

> + }
> +
> err = f2fs_gc_pinned_control(inode, gc_type, segno);
> if (err == -EAGAIN) {
> iput(inode);
> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index ac00423f117b..067600fed3d4 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -33,11 +33,26 @@ bool f2fs_may_inline_data(struct inode *inode)
> return !f2fs_post_read_required(inode);
> }
>
> -bool f2fs_sanity_check_inline_data(struct inode *inode)
> +static bool has_node_blocks(struct inode *inode, struct page *ipage)
> +{
> + struct f2fs_inode *ri = F2FS_INODE(ipage);
> + int i;
> +
> + for (i = 0; i < DEF_NIDS_PER_INODE; i++) {
> + if (ri->i_nid[i])
> + return true;
> + }
> + return false;
> +}
> +
> +bool f2fs_sanity_check_inline_data(struct inode *inode, struct page *ipage)
> {
> if (!f2fs_has_inline_data(inode))
> return false;
>
> + if (has_node_blocks(inode, ipage))
> + return false;
> +
> if (!support_inline_data(inode))
> return true;
>
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index c26effdce9aa..1423cd27a477 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -343,7 +343,7 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
> }
> }
>
> - if (f2fs_sanity_check_inline_data(inode)) {
> + if (f2fs_sanity_check_inline_data(inode, node_page)) {
> f2fs_warn(sbi, "%s: inode (ino=%lx, mode=%u) should not have inline_data, run fsck to fix",
> __func__, inode->i_ino, inode->i_mode);
> return false;
> --
> 2.40.1