This is a note to let you know that I've just added the patch titled
cifs: Fix UAF in cifs_demultiplex_thread()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-fix-uaf-in-cifs_demultiplex_thread.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3b64ec142b0237c1722da38144144252c2343bc0
Author: Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx>
Date: Tue Sep 19 13:38:04 2023 -0500
cifs: Fix UAF in cifs_demultiplex_thread()
[ Upstream commit d527f51331cace562393a8038d870b3e9916686f ]
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+ #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: ec637e3ffb6b ("[CIFS] Avoid extra large buffer allocation (and memcpy) in cifs_readpages")
Reviewed-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 03f34ec63e10d..39602f39aea8f 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1776,6 +1776,7 @@ static inline bool is_retryable_error(int error)
#define MID_RETRY_NEEDED 8 /* session closed while this request out */
#define MID_RESPONSE_MALFORMED 0x10
#define MID_SHUTDOWN 0x20
+#define MID_RESPONSE_READY 0x40 /* ready for other process handle the rsp */
/* Flags */
#define MID_WAIT_CANCELLED 1 /* Cancelled while waiting for response */
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index e03ffcf7e201c..87aea456ee903 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -35,6 +35,8 @@
void
cifs_wake_up_task(struct mid_q_entry *mid)
{
+ if (mid->mid_state == MID_RESPONSE_RECEIVED)
+ mid->mid_state = MID_RESPONSE_READY;
wake_up_process(mid->callback_data);
}
@@ -87,7 +89,8 @@ static void __release_mid(struct kref *refcount)
struct TCP_Server_Info *server = midEntry->server;
if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) &&
- midEntry->mid_state == MID_RESPONSE_RECEIVED &&
+ (midEntry->mid_state == MID_RESPONSE_RECEIVED ||
+ midEntry->mid_state == MID_RESPONSE_READY) &&
server->ops->handle_cancelled_mid)
server->ops->handle_cancelled_mid(midEntry, server);
@@ -759,7 +762,8 @@ wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
int error;
error = wait_event_state(server->response_q,
- midQ->mid_state != MID_REQUEST_SUBMITTED,
+ midQ->mid_state != MID_REQUEST_SUBMITTED &&
+ midQ->mid_state != MID_RESPONSE_RECEIVED,
(TASK_KILLABLE|TASK_FREEZABLE_UNSAFE));
if (error < 0)
return -ERESTARTSYS;
@@ -912,7 +916,7 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
spin_lock(&server->mid_lock);
switch (mid->mid_state) {
- case MID_RESPONSE_RECEIVED:
+ case MID_RESPONSE_READY:
spin_unlock(&server->mid_lock);
return rc;
case MID_RETRY_NEEDED:
@@ -1011,6 +1015,9 @@ cifs_compound_callback(struct mid_q_entry *mid)
credits.instance = server->reconnect_instance;
add_credits(server, &credits, mid->optype);
+
+ if (mid->mid_state == MID_RESPONSE_RECEIVED)
+ mid->mid_state = MID_RESPONSE_READY;
}
static void
@@ -1206,7 +1213,8 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
send_cancel(server, &rqst[i], midQ[i]);
spin_lock(&server->mid_lock);
midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
- if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
+ if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
+ midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
midQ[i]->callback = cifs_cancelled_callback;
cancelled_mid[i] = true;
credits[i].value = 0;
@@ -1227,7 +1235,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
}
if (!midQ[i]->resp_buf ||
- midQ[i]->mid_state != MID_RESPONSE_RECEIVED) {
+ midQ[i]->mid_state != MID_RESPONSE_READY) {
rc = -EIO;
cifs_dbg(FYI, "Bad MID state?\n");
goto out;
@@ -1414,7 +1422,8 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
if (rc != 0) {
send_cancel(server, &rqst, midQ);
spin_lock(&server->mid_lock);
- if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
+ if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
+ midQ->mid_state == MID_RESPONSE_RECEIVED) {
/* no longer considered to be "in-flight" */
midQ->callback = release_mid;
spin_unlock(&server->mid_lock);
@@ -1431,7 +1440,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
}
if (!midQ->resp_buf || !out_buf ||
- midQ->mid_state != MID_RESPONSE_RECEIVED) {
+ midQ->mid_state != MID_RESPONSE_READY) {
rc = -EIO;
cifs_server_dbg(VFS, "Bad MID state?\n");
goto out;
@@ -1555,14 +1564,16 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
/* Wait for a reply - allow signals to interrupt. */
rc = wait_event_interruptible(server->response_q,
- (!(midQ->mid_state == MID_REQUEST_SUBMITTED)) ||
+ (!(midQ->mid_state == MID_REQUEST_SUBMITTED ||
+ midQ->mid_state == MID_RESPONSE_RECEIVED)) ||
((server->tcpStatus != CifsGood) &&
(server->tcpStatus != CifsNew)));
/* Were we interrupted by a signal ? */
spin_lock(&server->srv_lock);
if ((rc == -ERESTARTSYS) &&
- (midQ->mid_state == MID_REQUEST_SUBMITTED) &&
+ (midQ->mid_state == MID_REQUEST_SUBMITTED ||
+ midQ->mid_state == MID_RESPONSE_RECEIVED) &&
((server->tcpStatus == CifsGood) ||
(server->tcpStatus == CifsNew))) {
spin_unlock(&server->srv_lock);
@@ -1593,7 +1604,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
if (rc) {
send_cancel(server, &rqst, midQ);
spin_lock(&server->mid_lock);
- if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
+ if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
+ midQ->mid_state == MID_RESPONSE_RECEIVED) {
/* no longer considered to be "in-flight" */
midQ->callback = release_mid;
spin_unlock(&server->mid_lock);
@@ -1613,7 +1625,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
return rc;
/* rcvd frame is ok */
- if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_RECEIVED) {
+ if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_READY) {
rc = -EIO;
cifs_tcon_dbg(VFS, "Bad MID state?\n");
goto out;
