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z00467499gregkh
z00467499
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gregkh
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cifs: Fix UAF in cifs_demultiplex_thread()
commit d527f51 upstream. There is a UAF when xfstests on cifs: BUG: KASAN: use-after-free in smb2_is_network_name_deleted+0x27/0x160 Read of size 4 at addr ffff88810103fc08 by task cifsd/923 CPU: 1 PID: 923 Comm: cifsd Not tainted 6.1.0-rc4+ torvalds#45 ... Call Trace: <TASK> dump_stack_lvl+0x34/0x44 print_report+0x171/0x472 kasan_report+0xad/0x130 kasan_check_range+0x145/0x1a0 smb2_is_network_name_deleted+0x27/0x160 cifs_demultiplex_thread.cold+0x172/0x5a4 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 </TASK> Allocated by task 923: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 __kasan_slab_alloc+0x54/0x60 kmem_cache_alloc+0x147/0x320 mempool_alloc+0xe1/0x260 cifs_small_buf_get+0x24/0x60 allocate_buffers+0xa1/0x1c0 cifs_demultiplex_thread+0x199/0x10d0 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 Freed by task 921: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x2a/0x40 ____kasan_slab_free+0x143/0x1b0 kmem_cache_free+0xe3/0x4d0 cifs_small_buf_release+0x29/0x90 SMB2_negotiate+0x8b7/0x1c60 smb2_negotiate+0x51/0x70 cifs_negotiate_protocol+0xf0/0x160 cifs_get_smb_ses+0x5fa/0x13c0 mount_get_conns+0x7a/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 The UAF is because: mount(pid: 921) | cifsd(pid: 923) -------------------------------|------------------------------- | cifs_demultiplex_thread SMB2_negotiate | cifs_send_recv | compound_send_recv | smb_send_rqst | wait_for_response | wait_event_state [1] | | standard_receive3 | cifs_handle_standard | handle_mid | mid->resp_buf = buf; [2] | dequeue_mid [3] KILL the process [4] | resp_iov[i].iov_base = buf | free_rsp_buf [5] | | is_network_name_deleted [6] | callback 1. After send request to server, wait the response until mid->mid_state != SUBMITTED; 2. Receive response from server, and set it to mid; 3. Set the mid state to RECEIVED; 4. Kill the process, the mid state already RECEIVED, get 0; 5. Handle and release the negotiate response; 6. UAF. It can be easily reproduce with add some delay in [3] - [6]. Only sync call has the problem since async call's callback is executed in cifsd process. Add an extra state to mark the mid state to READY before wakeup the waitter, then it can get the resp safely. Fixes: ec637e3 ("[CIFS] Avoid extra large buffer allocation (and memcpy) in cifs_readpages") Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com> [fs/cifs was moved to fs/smb/client since 38c8a9a ("smb: move client and server files to common directory fs/smb"). We apply the patch to fs/cifs with some minor context changes.] Signed-off-by: He Zhe <zhe.he@windriver.com> Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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‎fs/cifs/cifsglob.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1768,6 +1768,7 @@ static inline bool is_retryable_error(int error)
17681768
#define MID_RETRY_NEEDED 8 /* session closed while this request out */
17691769
#define MID_RESPONSE_MALFORMED 0x10
17701770
#define MID_SHUTDOWN 0x20
1771+
#define MID_RESPONSE_READY 0x40 /* ready for other process handle the rsp */
17711772

17721773
/* Flags */
17731774
#define MID_WAIT_CANCELLED 1 /* Cancelled while waiting for response */

‎fs/cifs/transport.c‎

Lines changed: 23 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -47,6 +47,8 @@
4747
void
4848
cifs_wake_up_task(struct mid_q_entry *mid)
4949
{
50+
if (mid->mid_state == MID_RESPONSE_RECEIVED)
51+
mid->mid_state = MID_RESPONSE_READY;
5052
wake_up_process(mid->callback_data);
5153
}
5254

@@ -99,7 +101,8 @@ static void _cifs_mid_q_entry_release(struct kref *refcount)
99101
struct TCP_Server_Info *server = midEntry->server;
100102

101103
if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) &&
102-
midEntry->mid_state == MID_RESPONSE_RECEIVED &&
104+
(midEntry->mid_state == MID_RESPONSE_RECEIVED ||
105+
midEntry->mid_state == MID_RESPONSE_READY) &&
103106
server->ops->handle_cancelled_mid)
104107
server->ops->handle_cancelled_mid(midEntry, server);
105108

@@ -733,7 +736,8 @@ wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
733736
int error;
734737

735738
error = wait_event_freezekillable_unsafe(server->response_q,
736-
midQ->mid_state != MID_REQUEST_SUBMITTED);
739+
midQ->mid_state != MID_REQUEST_SUBMITTED &&
740+
midQ->mid_state != MID_RESPONSE_RECEIVED);
737741
if (error < 0)
738742
return -ERESTARTSYS;
739743

@@ -885,7 +889,7 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
885889

886890
spin_lock(&GlobalMid_Lock);
887891
switch (mid->mid_state) {
888-
case MID_RESPONSE_RECEIVED:
892+
case MID_RESPONSE_READY:
889893
spin_unlock(&GlobalMid_Lock);
890894
return rc;
891895
case MID_RETRY_NEEDED:
@@ -984,6 +988,9 @@ cifs_compound_callback(struct mid_q_entry *mid)
984988
credits.instance = server->reconnect_instance;
985989

986990
add_credits(server, &credits, mid->optype);
991+
992+
if (mid->mid_state == MID_RESPONSE_RECEIVED)
993+
mid->mid_state = MID_RESPONSE_READY;
987994
}
988995

989996
static void
@@ -1172,7 +1179,8 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
11721179
send_cancel(server, &rqst[i], midQ[i]);
11731180
spin_lock(&GlobalMid_Lock);
11741181
midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
1175-
if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
1182+
if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
1183+
midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
11761184
midQ[i]->callback = cifs_cancelled_callback;
11771185
cancelled_mid[i] = true;
11781186
credits[i].value = 0;
@@ -1193,7 +1201,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
11931201
}
11941202

11951203
if (!midQ[i]->resp_buf ||
1196-
midQ[i]->mid_state != MID_RESPONSE_RECEIVED) {
1204+
midQ[i]->mid_state != MID_RESPONSE_READY) {
11971205
rc = -EIO;
11981206
cifs_dbg(FYI, "Bad MID state?\n");
11991207
goto out;
@@ -1372,7 +1380,8 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
13721380
if (rc != 0) {
13731381
send_cancel(server, &rqst, midQ);
13741382
spin_lock(&GlobalMid_Lock);
1375-
if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
1383+
if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
1384+
midQ->mid_state == MID_RESPONSE_RECEIVED) {
13761385
/* no longer considered to be "in-flight" */
13771386
midQ->callback = DeleteMidQEntry;
13781387
spin_unlock(&GlobalMid_Lock);
@@ -1389,7 +1398,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
13891398
}
13901399

13911400
if (!midQ->resp_buf || !out_buf ||
1392-
midQ->mid_state != MID_RESPONSE_RECEIVED) {
1401+
midQ->mid_state != MID_RESPONSE_READY) {
13931402
rc = -EIO;
13941403
cifs_server_dbg(VFS, "Bad MID state?\n");
13951404
goto out;
@@ -1509,13 +1518,15 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
15091518

15101519
/* Wait for a reply - allow signals to interrupt. */
15111520
rc = wait_event_interruptible(server->response_q,
1512-
(!(midQ->mid_state == MID_REQUEST_SUBMITTED)) ||
1521+
(!(midQ->mid_state == MID_REQUEST_SUBMITTED ||
1522+
midQ->mid_state == MID_RESPONSE_RECEIVED)) ||
15131523
((server->tcpStatus != CifsGood) &&
15141524
(server->tcpStatus != CifsNew)));
15151525

15161526
/* Were we interrupted by a signal ? */
15171527
if ((rc == -ERESTARTSYS) &&
1518-
(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
1528+
(midQ->mid_state == MID_REQUEST_SUBMITTED ||
1529+
midQ->mid_state == MID_RESPONSE_RECEIVED) &&
15191530
((server->tcpStatus == CifsGood) ||
15201531
(server->tcpStatus == CifsNew))) {
15211532

@@ -1545,7 +1556,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
15451556
if (rc) {
15461557
send_cancel(server, &rqst, midQ);
15471558
spin_lock(&GlobalMid_Lock);
1548-
if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
1559+
if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
1560+
midQ->mid_state == MID_RESPONSE_RECEIVED) {
15491561
/* no longer considered to be "in-flight" */
15501562
midQ->callback = DeleteMidQEntry;
15511563
spin_unlock(&GlobalMid_Lock);
@@ -1563,7 +1575,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
15631575
return rc;
15641576

15651577
/* rcvd frame is ok */
1566-
if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_RECEIVED) {
1578+
if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_READY) {
15671579
rc = -EIO;
15681580
cifs_tcon_dbg(VFS, "Bad MID state?\n");
15691581
goto out;

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