Commit 4a4e0328 authored by Deepanshu Kartikey's avatar Deepanshu Kartikey Committed by Viacheslav Dubeyko
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nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map 



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: default avatar <syzbot+4b4093b1f24ad789bf37@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=4b4093b1f24ad789bf37


Tested-by: default avatar <syzbot+4b4093b1f24ad789bf37@syzkaller.appspotmail.com>
Fixes: e897be17 ("nilfs2: fix lockdep warnings in page operations for btree nodes")
Signed-off-by: default avatarDeepanshu Kartikey <Kartikey406@gmail.com>
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarViacheslav Dubeyko <slava@dubeyko.com>
parent 6de23f81

fs/nilfs2/dat.c

+3 −0
Original line number Diff line number Diff line
@@ -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;