From: Pavel Skripkin paskripkin@gmail.com
commit 321460ca3b55f48b3ba6008248264ab2bd6407d9 upstream.
If ntfs_fill_super() wasn't called then sbi->sb will be equal to NULL. Code should check this ptr before dereferencing. Syzbot hit this issue via passing wrong mount param as can be seen from log below
Fail log: ntfs3: Unknown parameter 'iochvrset' general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] CPU: 1 PID: 3589 Comm: syz-executor210 Not tainted 5.18.0-rc3-syzkaller-00016-gb253435746d9 #0 ... Call Trace: <TASK> put_ntfs+0x1ed/0x2a0 fs/ntfs3/super.c:463 ntfs_fs_free+0x6a/0xe0 fs/ntfs3/super.c:1363 put_fs_context+0x119/0x7a0 fs/fs_context.c:469 do_new_mount+0x2b4/0xad0 fs/namespace.c:3044 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline]
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block") Reported-and-tested-by: syzbot+c95173762127ad76a824@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Signed-off-by: Konstantin Komarov almaz.alexandrovich@paragon-software.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ntfs3/fsntfs.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/ntfs3/fsntfs.c +++ b/fs/ntfs3/fsntfs.c @@ -831,10 +831,15 @@ int ntfs_update_mftmirr(struct ntfs_sb_i { int err; struct super_block *sb = sbi->sb; - u32 blocksize = sb->s_blocksize; + u32 blocksize; sector_t block1, block2; u32 bytes;
+ if (!sb) + return -EINVAL; + + blocksize = sb->s_blocksize; + if (!(sbi->flags & NTFS_FLAGS_MFTMIRR)) return 0;