Commit f79abe9f authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Xia Fukun
Browse files

nilfs2: add missing check for inode numbers on directory entries 

stable inclusion
from stable-v5.10.223
commit 2f2fa9cf7c3537958a82fbe8c8595a5eb0861ad7
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGPRT
CVE: CVE-2024-42104

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=2f2fa9cf7c3537958a82fbe8c8595a5eb0861ad7

--------------------------------

commit bb76c6c274683c8570ad788f79d4b875bde0e458 upstream.

Syzbot reported that mounting and unmounting a specific pattern of
corrupted nilfs2 filesystem images causes a use-after-free of metadata
file inodes, which triggers a kernel bug in lru_add_fn().

As Jan Kara pointed out, this is because the link count of a metadata file
gets corrupted to 0, and nilfs_evict_inode(), which is called from iput(),
tries to delete that inode (ifile inode in this case).

The inconsistency occurs because directories containing the inode numbers
of these metadata files that should not be visible in the namespace are
read without checking.

Fix this issue by treating the inode numbers of these internal files as
errors in the sanity check helper when reading directory folios/pages.

Also thanks to Hillf Danton and Matthew Wilcox for their initial mm-layer
analysis.

Link: https://lkml.kernel.org/r/20240623051135.4180-3-konishi.ryusuke@gmail.com


Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: default avatar <syzbot+d79afb004be235636ee8@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=d79afb004be235636ee8


Reported-by: default avatarJan Kara <jack@suse.cz>
Closes: https://lkml.kernel.org/r/20240617075758.wewhukbrjod5fp5o@quack3


Tested-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarXia Fukun <xiafukun@huawei.com>
parent a0db09dd

fs/nilfs2/dir.c

+6 −0
Original line number Diff line number Diff line
@@ -143,6 +143,9 @@ static bool nilfs_check_page(struct page *page) 
			goto Enamelen;

		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))

			goto Espan;

		if (unlikely(p->inode &&

			     NILFS_PRIVATE_INODE(le64_to_cpu(p->inode))))

			goto Einumber;

	}

	if (offs != limit)

		goto Eend;
@@ -168,6 +171,9 @@ static bool nilfs_check_page(struct page *page) 
	goto bad_entry;

Espan:

	error = "directory entry across blocks";

	goto bad_entry;

Einumber:

	error = "disallowed inode number";

bad_entry:

	nilfs_error(sb,

		    "bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%d, name_len=%d",

fs/nilfs2/nilfs.h

+5 −0
Original line number Diff line number Diff line
@@ -121,6 +121,11 @@ enum { 
	((ino) >= NILFS_FIRST_INO(sb) ||				\

	 ((ino) < NILFS_USER_INO && (NILFS_SYS_INO_BITS & BIT(ino))))



#define NILFS_PRIVATE_INODE(ino) ({					\

	ino_t __ino = (ino);						\

	((__ino) < NILFS_USER_INO && (__ino) != NILFS_ROOT_INO &&	\

	 (__ino) != NILFS_SKETCH_INO); })



/**

 * struct nilfs_transaction_info: context information for synchronization

 * @ti_magic: Magic number