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author | Vincent Whitchurch <vincent.whitchurch@axis.com> | 2020-01-23 19:09:06 +0300 |
---|---|---|
committer | Steve French <stfrench@microsoft.com> | 2020-01-27 04:24:17 +0300 |
commit | f1f27ad74557e39f67a8331a808b860f89254f2d (patch) | |
tree | 432df7a17ce6dcf51d3eaa6b30b2e3be2dc82aad /fs/cifs/cifsglob.h | |
parent | 050d2a8b6992fd012773e75de9f82d45e3b3dfff (diff) | |
download | linux-f1f27ad74557e39f67a8331a808b860f89254f2d.tar.xz |
CIFS: Fix task struct use-after-free on reconnect
The task which created the MID may be gone by the time cifsd attempts to
call the callbacks on MIDs from cifs_reconnect().
This leads to a use-after-free of the task struct in cifs_wake_up_task:
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x31a0/0x3270
Read of size 8 at addr ffff8880103e3a68 by task cifsd/630
CPU: 0 PID: 630 Comm: cifsd Not tainted 5.5.0-rc6+ #119
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
dump_stack+0x8e/0xcb
print_address_description.constprop.5+0x1d3/0x3c0
? __lock_acquire+0x31a0/0x3270
__kasan_report+0x152/0x1aa
? __lock_acquire+0x31a0/0x3270
? __lock_acquire+0x31a0/0x3270
kasan_report+0xe/0x20
__lock_acquire+0x31a0/0x3270
? __wake_up_common+0x1dc/0x630
? _raw_spin_unlock_irqrestore+0x4c/0x60
? mark_held_locks+0xf0/0xf0
? _raw_spin_unlock_irqrestore+0x39/0x60
? __wake_up_common_lock+0xd5/0x130
? __wake_up_common+0x630/0x630
lock_acquire+0x13f/0x330
? try_to_wake_up+0xa3/0x19e0
_raw_spin_lock_irqsave+0x38/0x50
? try_to_wake_up+0xa3/0x19e0
try_to_wake_up+0xa3/0x19e0
? cifs_compound_callback+0x178/0x210
? set_cpus_allowed_ptr+0x10/0x10
cifs_reconnect+0xa1c/0x15d0
? generic_ip_connect+0x1860/0x1860
? rwlock_bug.part.0+0x90/0x90
cifs_readv_from_socket+0x479/0x690
cifs_read_from_socket+0x9d/0xe0
? cifs_readv_from_socket+0x690/0x690
? mempool_resize+0x690/0x690
? rwlock_bug.part.0+0x90/0x90
? memset+0x1f/0x40
? allocate_buffers+0xff/0x340
cifs_demultiplex_thread+0x388/0x2a50
? cifs_handle_standard+0x610/0x610
? rcu_read_lock_held_common+0x120/0x120
? mark_lock+0x11b/0xc00
? __lock_acquire+0x14ed/0x3270
? __kthread_parkme+0x78/0x100
? lockdep_hardirqs_on+0x3e8/0x560
? lock_downgrade+0x6a0/0x6a0
? lockdep_hardirqs_on+0x3e8/0x560
? _raw_spin_unlock_irqrestore+0x39/0x60
? cifs_handle_standard+0x610/0x610
kthread+0x2bb/0x3a0
? kthread_create_worker_on_cpu+0xc0/0xc0
ret_from_fork+0x3a/0x50
Allocated by task 649:
save_stack+0x19/0x70
__kasan_kmalloc.constprop.5+0xa6/0xf0
kmem_cache_alloc+0x107/0x320
copy_process+0x17bc/0x5370
_do_fork+0x103/0xbf0
__x64_sys_clone+0x168/0x1e0
do_syscall_64+0x9b/0xec0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 0:
save_stack+0x19/0x70
__kasan_slab_free+0x11d/0x160
kmem_cache_free+0xb5/0x3d0
rcu_core+0x52f/0x1230
__do_softirq+0x24d/0x962
The buggy address belongs to the object at ffff8880103e32c0
which belongs to the cache task_struct of size 6016
The buggy address is located 1960 bytes inside of
6016-byte region [ffff8880103e32c0, ffff8880103e4a40)
The buggy address belongs to the page:
page:ffffea000040f800 refcount:1 mapcount:0 mapping:ffff8880108da5c0
index:0xffff8880103e4c00 compound_mapcount: 0
raw: 4000000000010200 ffffea00001f2208 ffffea00001e3408 ffff8880108da5c0
raw: ffff8880103e4c00 0000000000050003 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8880103e3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880103e3980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880103e3a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880103e3a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880103e3b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
This can be reliably reproduced by adding the below delay to
cifs_reconnect(), running find(1) on the mount, restarting the samba
server while find is running, and killing find during the delay:
spin_unlock(&GlobalMid_Lock);
mutex_unlock(&server->srv_mutex);
+ msleep(10000);
+
cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
list_for_each_safe(tmp, tmp2, &retry_list) {
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
Fix this by holding a reference to the task struct until the MID is
freed.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Diffstat (limited to 'fs/cifs/cifsglob.h')
-rw-r--r-- | fs/cifs/cifsglob.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 40705e862451..239338d57086 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1588,6 +1588,7 @@ struct mid_q_entry { mid_callback_t *callback; /* call completion callback */ mid_handle_t *handle; /* call handle mid callback */ void *callback_data; /* general purpose pointer for callback */ + struct task_struct *creator; void *resp_buf; /* pointer to received SMB header */ unsigned int resp_buf_size; int mid_state; /* wish this were enum but can not pass to wait_event */ |