From: Steve French stfrench@microsoft.com
[ Upstream commit e8f5f849ffce24490eb9449e98312b66c0dba76f ]
With deferred close we can have closes that race with lease breaks, and so with the current checks for whether to send the lease response, oplock_response(), this can mean that an unmount (kill_sb) can occur just before we were checking if the tcon->ses is valid. See below:
[Fri Aug 4 04:12:50 2023] RIP: 0010:cifs_oplock_break+0x1f7/0x5b0 [cifs] [Fri Aug 4 04:12:50 2023] Code: 7d a8 48 8b 7d c0 c0 e9 02 48 89 45 b8 41 89 cf e8 3e f5 ff ff 4c 89 f7 41 83 e7 01 e8 82 b3 03 f2 49 8b 45 50 48 85 c0 74 5e <48> 83 78 60 00 74 57 45 84 ff 75 52 48 8b 43 98 48 83 eb 68 48 39 [Fri Aug 4 04:12:50 2023] RSP: 0018:ffffb30607ddbdf8 EFLAGS: 00010206 [Fri Aug 4 04:12:50 2023] RAX: 632d223d32612022 RBX: ffff97136944b1e0 RCX: 0000000080100009 [Fri Aug 4 04:12:50 2023] RDX: 0000000000000001 RSI: 0000000080100009 RDI: ffff97136944b188 [Fri Aug 4 04:12:50 2023] RBP: ffffb30607ddbe58 R08: 0000000000000001 R09: ffffffffc08e0900 [Fri Aug 4 04:12:50 2023] R10: 0000000000000001 R11: 000000000000000f R12: ffff97136944b138 [Fri Aug 4 04:12:50 2023] R13: ffff97149147c000 R14: ffff97136944b188 R15: 0000000000000000 [Fri Aug 4 04:12:50 2023] FS: 0000000000000000(0000) GS:ffff9714f7c00000(0000) knlGS:0000000000000000 [Fri Aug 4 04:12:50 2023] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [Fri Aug 4 04:12:50 2023] CR2: 00007fd8de9c7590 CR3: 000000011228e000 CR4: 0000000000350ef0 [Fri Aug 4 04:12:50 2023] Call Trace: [Fri Aug 4 04:12:50 2023] <TASK> [Fri Aug 4 04:12:50 2023] process_one_work+0x225/0x3d0 [Fri Aug 4 04:12:50 2023] worker_thread+0x4d/0x3e0 [Fri Aug 4 04:12:50 2023] ? process_one_work+0x3d0/0x3d0 [Fri Aug 4 04:12:50 2023] kthread+0x12a/0x150 [Fri Aug 4 04:12:50 2023] ? set_kthread_struct+0x50/0x50 [Fri Aug 4 04:12:50 2023] ret_from_fork+0x22/0x30 [Fri Aug 4 04:12:50 2023] </TASK>
To fix this change the ordering of the checks before sending the oplock_response to first check if the openFileList is empty.
Fixes: da787d5b7498 ("SMB3: Do not send lease break acknowledgment if all file handles have been closed") Suggested-by: Bharath SM bharathsm@microsoft.com Reviewed-by: Bharath SM bharathsm@microsoft.com Reviewed-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/file.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c index d554bca7e07eb..4e9d26d4404ab 100644 --- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -4878,9 +4878,11 @@ void cifs_oplock_break(struct work_struct *work) struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo, oplock_break); struct inode *inode = d_inode(cfile->dentry); + struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); struct cifsInodeInfo *cinode = CIFS_I(inode); - struct cifs_tcon *tcon = tlink_tcon(cfile->tlink); - struct TCP_Server_Info *server = tcon->ses->server; + struct cifs_tcon *tcon; + struct TCP_Server_Info *server; + struct tcon_link *tlink; int rc = 0; bool purge_cache = false, oplock_break_cancelled; __u64 persistent_fid, volatile_fid; @@ -4889,6 +4891,12 @@ void cifs_oplock_break(struct work_struct *work) wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS, TASK_UNINTERRUPTIBLE);
+ tlink = cifs_sb_tlink(cifs_sb); + if (IS_ERR(tlink)) + goto out; + tcon = tlink_tcon(tlink); + server = tcon->ses->server; + server->ops->downgrade_oplock(server, cinode, cfile->oplock_level, cfile->oplock_epoch, &purge_cache);
@@ -4938,18 +4946,19 @@ void cifs_oplock_break(struct work_struct *work) /* * MS-SMB2 3.2.5.19.1 and 3.2.5.19.2 (and MS-CIFS 3.2.5.42) do not require * an acknowledgment to be sent when the file has already been closed. - * check for server null, since can race with kill_sb calling tree disconnect. */ spin_lock(&cinode->open_file_lock); - if (tcon->ses && tcon->ses->server && !oplock_break_cancelled && - !list_empty(&cinode->openFileList)) { + /* check list empty since can race with kill_sb calling tree disconnect */ + if (!oplock_break_cancelled && !list_empty(&cinode->openFileList)) { spin_unlock(&cinode->open_file_lock); - rc = tcon->ses->server->ops->oplock_response(tcon, persistent_fid, - volatile_fid, net_fid, cinode); + rc = server->ops->oplock_response(tcon, persistent_fid, + volatile_fid, net_fid, cinode); cifs_dbg(FYI, "Oplock release rc = %d\n", rc); } else spin_unlock(&cinode->open_file_lock);
+ cifs_put_tlink(tlink); +out: cifs_done_oplock_break(cinode); }