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Message-ID: <718222b6-0291-dcdc-30d8-9b2a7e4e434c@paragon-software.com> Date: Mon, 26 Dec 2022 18:59:16 +0400 From: Konstantin Komarov <almaz.alexandrovich@...agon-software.com> To: Peng Zhang <zhangpeng362@...wei.com>, <kari.argillander@...il.com> CC: <ntfs3@...ts.linux.dev>, <linux-kernel@...r.kernel.org>, <sunnanyong@...wei.com>, <wangkefeng.wang@...wei.com>, <syzbot+a8f26a403c169b7593fe@...kaller.appspotmail.com> Subject: Re: [PATCH] fs/ntfs3: Fix null-ptr-deref on inode->i_op in ntfs_lookup() On 25.11.2022 14:21, Peng Zhang wrote: > From: ZhangPeng <zhangpeng362@...wei.com> > > 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@...kaller.appspotmail.com > Signed-off-by: ZhangPeng <zhangpeng362@...wei.com> > --- > fs/ntfs3/namei.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c > index bc22cc321a74..7760aedc0672 100644 > --- a/fs/ntfs3/namei.c > +++ b/fs/ntfs3/namei.c > @@ -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); > } > Applied, thanks!
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