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All release_mid() callers seem to hold a reference of @mid so there is
no need to call kref_put(&mid->refcount, __release_mid) under
@server->mid_lock spinlock. If they don't, then an use-after-free bug
would have occurred anyways.
By getting rid of such spinlock also fixes a potential deadlock as
shown below
CPU 0 CPU 1
------------------------------------------------------------------
cifs_demultiplex_thread() cifs_debug_data_proc_show()
release_mid()
spin_lock(&server->mid_lock);
spin_lock(&cifs_tcp_ses_lock)
spin_lock(&server->mid_lock)
__release_mid()
smb2_find_smb_tcon()
spin_lock(&cifs_tcp_ses_lock) *deadlock*
Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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@manguebit.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Minor cleanup pointed out by checkpatch (repeated words, missing blank
lines) in smb2pdu.c and old header location referred to in transport.c
Signed-off-by: Steve French <stfrench@microsoft.com>
Clang warns about exceeded stack frame size
fs/smb/client/transport.c:420:1: warning: stack frame size (1048)
exceeds limit (1024) in 'smb_send_rqst' [-Wframe-larger-than]
Fix this by allocating a structure that will hold transform header and
compound requests.
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
All the server credits and in-flight info is protected by req_lock.
Once the req_lock is held, and we've determined that we have enough
credits to continue, this lock cannot be dropped till we've made the
changes to credits and in-flight count.
However, we used to drop the lock in order to avoid deadlock with
the recent srv_lock. This could cause the checks already made to be
invalidated.
Fixed it by moving the server status check to before locking req_lock.
Fixes: d7d7a66aacd6 ("cifs: avoid use of global locks for high contention data")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Because do_gettimeofday has been removed and replaced by ktime_get_real_ts64,
So just remove the comment as it's not needed now.
Signed-off-by: 鑫华 <jixianghua@xfusion.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko
and helper modules) to new fs/smb subdirectory:
fs/cifs --> fs/smb/client
fs/ksmbd --> fs/smb/server
fs/smbfs_common --> fs/smb/common
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
