| Message ID | 20200921082637.26009-1-qiang.zhang@windriver.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: Fix missing close devices | expand |
On 21/09/2020 10:27, qiang.zhang@windriver.com wrote: > From: Zqiang <qiang.zhang@windriver.com> > > When the btrfs fill super error, we should first close devices and > then call deactivate_locked_super func to free fs_info. > > Signed-off-by: Zqiang <qiang.zhang@windriver.com> > --- > fs/btrfs/super.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 8840a4fa81eb..3bfd54e8f388 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -1675,6 +1675,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, > error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL); > security_free_mnt_opts(&new_sec_opts); > if (error) { > + btrfs_close_devices(fs_devices); > deactivate_locked_super(s); > return ERR_PTR(error); > } > I think this is the fix for the syzkaller issue: Reported-by: syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com
On 21/09/2020 11:14, Zhang, Qiang wrote: > > > ________________________________________ > 发件人: Johannes Thumshirn <Johannes.Thumshirn@wdc.com> > 发送时间: 2020年9月21日 16:52 > 收件人: Zhang, Qiang; clm@fb.com; josef@toxicpanda.com; dsterba@suse.com > 抄送: linux-btrfs@vger.kernel.org; linux-kernel@vger.kernel.org > 主题: Re: [PATCH] btrfs: Fix missing close devices > > On 21/09/2020 10:27, qiang.zhang@windriver.com wrote: >> From: Zqiang <qiang.zhang@windriver.com> >> >> When the btrfs fill super error, we should first close devices and >> then call deactivate_locked_super func to free fs_info. >> >> Signed-off-by: Zqiang <qiang.zhang@windriver.com> >> --- >> fs/btrfs/super.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c >> index 8840a4fa81eb..3bfd54e8f388 100644 >> --- a/fs/btrfs/super.c >> +++ b/fs/btrfs/super.c >> @@ -1675,6 +1675,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, >> error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL); >> security_free_mnt_opts(&new_sec_opts); >> if (error) { >> + btrfs_close_devices(fs_devices); >> deactivate_locked_super(s); >> return ERR_PTR(error); >> } >> > >> I think this is the fix for the syzkaller issue: >> Reported-by: syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com > > Please try this patch. > Nope, with this patch I get the following Null-ptr-deref: [ 39.065209] ================================================================== [ 39.066318] BUG: KASAN: null-ptr-deref in bdev_name.constprop.0+0xd4/0x240 [ 39.067307] Read of size 4 at addr 00000000000003ac by task syz-repro/273 [ 39.068289] [ 39.069602] ================================================================== [ 39.070837] BUG: kernel NULL pointer dereference, address: 00000000000003ac [ 39.071837] #PF: supervisor read access in kernel mode [ 39.072580] #PF: error_code(0x0000) - not-present page [ 39.073318] PGD 80000001cd3b1067 P4D 80000001cd3b1067 PUD 1c6de7067 PMD 0 [ 39.074306] Oops: 0000 [#1] SMP KASAN PTI [ 39.074887] CPU: 0 PID: 273 Comm: syz-repro Tainted: G B 5.9.0-rc5+ #772 [ 39.076031] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014 [ 39.077638] RIP: 0010:bdev_name.constprop.0+0xd4/0x240 [ 39.078387] Code: ca 4c 89 4c 24 08 e8 0b e9 ff ff 48 89 df 49 89 c6 e8 40 42 c6 ff 49 8b ac 24 e0 00 00 00 48 8d bd ac 03 00 00 e8 2c 41 c6 ff <8b> 85 ac 03 00 00 4c 8b 4c 24 08 85 c0 0f 84 fe 00 00 00 4c 89 cf [ 39.080991] RSP: 0018:ffff8881f1a97878 EFLAGS: 00010286 [ 39.081728] RAX: 0000000000000001 RBX: ffff8881c9fb80e0 RCX: dffffc0000000000 [ 39.082725] RDX: 0000000000000007 RSI: 0000000000000004 RDI: ffffffff81acd784 [ 39.083717] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 39.084722] R10: fffffbfff0539591 R11: 0000000000000001 R12: ffff8881c9fb8000 [ 39.085711] R13: ffff8881ef6e2698 R14: ffff8881ef6e2680 R15: 0000000000000000 [ 39.086704] FS: 00007f5d36eb9540(0000) GS:ffff8881f7600000(0000) knlGS:0000000000000000 [ 39.087827] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 39.088623] CR2: 00000000000003ac CR3: 00000001ef552000 CR4: 00000000000006b0 [ 39.089607] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 39.090603] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 39.091583] Call Trace: [ 39.091943] ? mac_address_string+0x380/0x380 [ 39.092559] ? mark_held_locks+0x65/0x90 [ 39.093116] pointer+0x21c/0x650 [ 39.093578] ? format_decode+0x1cf/0x4e0 [ 39.094139] ? resource_string.isra.0+0xc10/0xc10 [ 39.094809] vsnprintf+0x2e0/0x820 [ 39.095292] ? pointer+0x650/0x650 [ 39.095785] snprintf+0x88/0xa0 [ 39.096234] ? vsprintf+0x10/0x10 [ 39.096708] ? rcu_read_lock_sched_held+0x3a/0x70 [ 39.097378] ? sget+0x200/0x240 [ 39.097908] ? btrfs_kill_super+0x30/0x30 [btrfs] [ 39.098644] btrfs_mount_root+0x442/0x5d0 [btrfs] [ 39.099377] ? parse_rescue_options+0x150/0x150 [btrfs] [ 39.100103] ? rcu_read_lock_sched_held+0x3a/0x70 [ 39.100759] ? vfs_parse_fs_string+0xbc/0xf0 [ 39.101355] ? kfree+0x1e0/0x310 [ 39.101816] ? vfs_parse_fs_string+0xbc/0xf0 [ 39.102493] ? parse_rescue_options+0x150/0x150 [btrfs] [ 39.103219] legacy_get_tree+0x7d/0xc0 [ 39.103750] vfs_get_tree+0x48/0x100 [ 39.104263] ? parse_monolithic_mount_data+0x1c/0x40 [ 39.104960] vfs_kern_mount.part.0+0x70/0xd0 [ 39.105649] btrfs_mount+0x187/0x550 [btrfs] [ 39.106268] ? mark_held_locks+0x24/0x90 [ 39.106918] ? btrfs_show_options+0x730/0x730 [btrfs] [ 39.107641] ? lockdep_hardirqs_on_prepare+0x146/0x240 [ 39.108368] ? strcmp+0x2e/0x50 [ 39.108810] ? rcu_read_lock_sched_held+0x3a/0x70 [ 39.109461] ? vfs_parse_fs_string+0xbc/0xf0 [ 39.110054] ? kfree+0x1e0/0x310 [ 39.110519] ? vfs_parse_fs_string+0xbc/0xf0 [ 39.111197] ? btrfs_show_options+0x730/0x730 [btrfs] [ 39.111898] legacy_get_tree+0x7d/0xc0 [ 39.112427] vfs_get_tree+0x48/0x100 [ 39.112928] path_mount+0xa37/0xfc0 [ 39.113422] ? strncpy_from_user+0xde/0x1f0 [ 39.114011] ? copy_mount_string+0x20/0x20 [ 39.114588] ? getname_flags+0xa7/0x220 [ 39.115132] ? _copy_from_user+0x8e/0xd0 [ 39.115686] __x64_sys_mount+0x16b/0x1a0 [ 39.116242] ? copy_mnt_ns+0x540/0x540 [ 39.116770] ? trace_hardirqs_on+0x34/0x130 [ 39.117370] do_syscall_64+0x33/0x40 [ 39.117886] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 39.118604] RIP: 0033:0x7f5d36df1eda
On 23/09/2020 08:03, Zhang, Qiang wrote: > Hello Johannes Thumshirn > > the crash happend in "snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev)" in btrfs_mount_root func, the "bdev" may be destroyed in btrfs_close_devices. > I think add btrfs_close_devices func before deactivate_locked_super is reasonable. > I'm not sure if that's another problem . > What's your point of view ？ > I think this is generally unneeded. Think of this call chain: deactivate_locked_super() `-> fs->kill_sb() `-> btrfs_kill_super() `-> kill_anon_super() `-> generic_shutdown_super() `-> sop->put_super() `-> btrfs_put_super() `-> close_ctree() `-> btrfs_close_devices()
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 8840a4fa81eb..3bfd54e8f388 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1675,6 +1675,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL); security_free_mnt_opts(&new_sec_opts); if (error) { + btrfs_close_devices(fs_devices); deactivate_locked_super(s); return ERR_PTR(error); }