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authorVegard Nossum <vegard.nossum@oracle.com>2016-08-22 12:47:43 +0200
committerJens Axboe <axboe@fb.com>2016-08-22 08:06:15 -0600
commite9e5e3fae8da7e237049e00e0bfc9e32fd808fe8 (patch)
tree6d46abeb0cfee60b60b9cd34d851536a46912f81 /fs
parentcbaaf6ef0e9fba6d842d4df07d3afaf1996b2181 (diff)
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bdev: fix NULL pointer dereference
I got this: kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) CPU: 0 PID: 5505 Comm: syz-executor Not tainted 4.8.0-rc2+ #161 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 task: ffff880113415940 task.stack: ffff880118350000 RIP: 0010:[<ffffffff8172cb32>] [<ffffffff8172cb32>] bd_mount+0x52/0xa0 RSP: 0018:ffff880118357ca0 EFLAGS: 00010207 RAX: dffffc0000000000 RBX: ffffffffffffffff RCX: ffffc90000bb6000 RDX: 0000000000000018 RSI: ffffffff846d6b20 RDI: 00000000000000c7 RBP: ffff880118357cb0 R08: ffff880115967c68 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801188211e8 R13: ffffffff847baa20 R14: ffff8801139cb000 R15: 0000000000000080 FS: 00007fa3ff6c0700(0000) GS:ffff88011aa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc1d8cc7e78 CR3: 0000000109f20000 CR4: 00000000000006f0 DR0: 000000000000001e DR1: 000000000000001e DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Stack: ffff880112cfd6c0 ffff8801188211e8 ffff880118357cf0 ffffffff8167f207 ffffffff816d7a1e ffff880112a413c0 ffffffff847baa20 ffff8801188211e8 0000000000000080 ffff880112cfd6c0 ffff880118357d38 ffffffff816dce0a Call Trace: [<ffffffff8167f207>] mount_fs+0x97/0x2e0 [<ffffffff816d7a1e>] ? alloc_vfsmnt+0x55e/0x760 [<ffffffff816dce0a>] vfs_kern_mount+0x7a/0x300 [<ffffffff83c3247c>] ? _raw_read_unlock+0x2c/0x50 [<ffffffff816dfc87>] do_mount+0x3d7/0x2730 [<ffffffff81235fd4>] ? trace_do_page_fault+0x1f4/0x3a0 [<ffffffff816df8b0>] ? copy_mount_string+0x40/0x40 [<ffffffff8161ea81>] ? memset+0x31/0x40 [<ffffffff816df73e>] ? copy_mount_options+0x1ee/0x320 [<ffffffff816e2a02>] SyS_mount+0xb2/0x120 [<ffffffff816e2950>] ? copy_mnt_ns+0x970/0x970 [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0 [<ffffffff83c3282a>] entry_SYSCALL64_slow_path+0x25/0x25 Code: 83 e8 63 1b fc ff 48 85 c0 48 89 c3 74 4c e8 56 35 d1 ff 48 8d bb c8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 36 4c 8b a3 c8 00 00 00 48 b8 00 00 00 00 00 fc RIP [<ffffffff8172cb32>] bd_mount+0x52/0xa0 RSP <ffff880118357ca0> ---[ end trace 13690ad962168b98 ]--- mount_pseudo() returns ERR_PTR(), not NULL, on error. Fixes: 3684aa7099e0 ("block-dev: enable writeback cgroup support") Cc: Shaohua Li <shli@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Cc: stable@vger.kernel.org Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/block_dev.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c3cdde87cc8c..e17bdbdfe9b1 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -646,7 +646,7 @@ static struct dentry *bd_mount(struct file_system_type *fs_type,
{
struct dentry *dent;
dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
- if (dent)
+ if (!IS_ERR(dent))
dent->d_sb->s_iflags |= SB_I_CGROUPWB;
return dent;
}