diff options
| author | Paulo Alcantara <pc@manguebit.com> | 2023-10-25 14:58:35 -0300 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2023-10-31 12:38:02 -0500 |
| commit | e6322fd177c6885a21dd4609dc5e5c973d1a2eb7 (patch) | |
| tree | ef37d8ba5db90d1c2eda090137ac422df0ad8d87 /fs/smb/client/transport.c | |
| parent | 72bc63f5e23a38b65ff2a201bdc11401d4223fa9 (diff) | |
smb: client: fix potential deadlock when releasing mids
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>
Diffstat (limited to 'fs/smb/client/transport.c')
| -rw-r--r-- | fs/smb/client/transport.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c index 14710afdc2a3..d553b7a54621 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -76,7 +76,7 @@ alloc_mid(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server) return temp; } -static void __release_mid(struct kref *refcount) +void __release_mid(struct kref *refcount) { struct mid_q_entry *midEntry = container_of(refcount, struct mid_q_entry, refcount); @@ -156,15 +156,6 @@ static void __release_mid(struct kref *refcount) mempool_free(midEntry, cifs_mid_poolp); } -void release_mid(struct mid_q_entry *mid) -{ - struct TCP_Server_Info *server = mid->server; - - spin_lock(&server->mid_lock); - kref_put(&mid->refcount, __release_mid); - spin_unlock(&server->mid_lock); -} - void delete_mid(struct mid_q_entry *mid) { |