For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: [PATCH] nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map
Author: kartikey406@gmail.com
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
The DAT inode's btree node cache (i_assoc_inode) is initialized lazily
during btree operations. However, nilfs_mdt_save_to_shadow_map()
assumes i_assoc_inode is already initialized when copying dirty pages
to the shadow map during GC.
If NILFS_IOCTL_CLEAN_SEGMENTS is called immediately after mount before
any btree operation has occurred on the DAT inode, i_assoc_inode is
NULL leading to a general protection fault.
Fix this by calling nilfs_attach_btree_node_cache() on the DAT inode
in nilfs_dat_read() at mount time, ensuring i_assoc_inode is always
initialized before any GC operation can use it.
Reported-by: syzbot+4b4093b1f24ad789bf37@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4b4093b1f24ad789bf37
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
---
fs/nilfs2/dat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/nilfs2/dat.c b/fs/nilfs2/dat.c
index 674380837ab9..888dc1831c86 100644
--- a/fs/nilfs2/dat.c
+++ b/fs/nilfs2/dat.c
@@ -524,6 +524,9 @@ int nilfs_dat_read(struct super_block *sb, size_t entry_size,
if (err)
goto failed;
+ err = nilfs_attach_btree_node_cache(dat);
+ if (err)
+ goto failed;
err = nilfs_read_inode_common(dat, raw_inode);
if (err)
goto failed;
--
2.43.0