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fs/ntfs3: Fix null-ptr-deref on inode->i_op in ntfs_lookup()

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[ Upstream commit 254e69f284d7270e0abdc023ee53b71401c3ba0c ]

Syzbot reported a null-ptr-deref bug:

ntfs3: loop0: Different NTFS' sector size (1024) and media sector size
(512)
ntfs3: loop0: Mark volume as dirty due to NTFS errors
general protection fault, probably for non-canonical address
0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
RIP: 0010:d_flags_for_inode fs/dcache.c:1980 [inline]
RIP: 0010:__d_add+0x5ce/0x800 fs/dcache.c:2796
Call Trace:
 <TASK>
 d_splice_alias+0x122/0x3b0 fs/dcache.c:3191
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x10e6/0x2df0 fs/namei.c:3688
 do_filp_open+0x264/0x4f0 fs/namei.c:3718
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_open fs/open.c:1334 [inline]
 __se_sys_open fs/open.c:1330 [inline]
 __x64_sys_open+0x221/0x270 fs/open.c:1330
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

If the MFT record of ntfs inode is not a base record, inode->i_op can be
NULL. And a null-ptr-deref may happen:

ntfs_lookup()
    dir_search_u() # inode->i_op is set to NULL
    d_splice_alias()
        __d_add()
            d_flags_for_inode() # inode->i_op->get_link null-ptr-deref

Fix this by adding a Check on inode->i_op before calling the
d_splice_alias() function.

Fixes: 4342306f0f0d ("fs/ntfs3: Add file operations and implementation")
Reported-by: syzbot+a8f26a403c169b7593fe@syzkaller.appspotmail.com
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
ZhangPeng 2022-11-25 10:21:59 +00:00 committed by Greg Kroah-Hartman
parent ce30b2f48b
commit f8d9e062a6
1 changed files with 10 additions and 0 deletions
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10
fs/ntfs3/namei.c
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@ -86,6 +86,16 @@ static struct dentry *ntfs_lookup(struct inode *dir, struct dentry *dentry,
__putname(uni);
}
/*
* Check for a null pointer
* If the MFT record of ntfs inode is not a base record, inode->i_op can be NULL.
* This causes null pointer dereference in d_splice_alias().
*/
if (!IS_ERR(inode) && inode->i_op == NULL) {
iput(inode);
inode = ERR_PTR(-EINVAL);
}
return d_splice_alias(inode, dentry);
}