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

[Chao Yu <chao@kernel.org>]

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;
+			}
+
 			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