cifs: Fix warning and UAF when destroy the MR list

[ Upstream commit 3e161c2 ]

If the MR allocate failed, the MR recovery work not initialized
and list not cleared. Then will be warning and UAF when release
the MR:

  WARNING: CPU: 4 PID: 824 at kernel/workqueue.c:3066 __flush_work.isra.0+0xf7/0x110
  CPU: 4 PID: 824 Comm: mount.cifs Not tainted 6.1.0-rc5+ #82
  RIP: 0010:__flush_work.isra.0+0xf7/0x110
  Call Trace:
   <TASK>
   __cancel_work_timer+0x2ba/0x2e0
   smbd_destroy+0x4e1/0x990
   _smbd_get_connection+0x1cbd/0x2110
   smbd_get_connection+0x21/0x40
   cifs_get_tcp_session+0x8ef/0xda0
   mount_get_conns+0x60/0x750
   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

  BUG: KASAN: use-after-free in smbd_destroy+0x4fc/0x990
  Read of size 8 at addr ffff88810b156a08 by task mount.cifs/824
  CPU: 4 PID: 824 Comm: mount.cifs Tainted: G        W          6.1.0-rc5+ #82
  Call Trace:
   dump_stack_lvl+0x34/0x44
   print_report+0x171/0x472
   kasan_report+0xad/0x130
   smbd_destroy+0x4fc/0x990
   _smbd_get_connection+0x1cbd/0x2110
   smbd_get_connection+0x21/0x40
   cifs_get_tcp_session+0x8ef/0xda0
   mount_get_conns+0x60/0x750
   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

  Allocated by task 824:
   kasan_save_stack+0x1e/0x40
   kasan_set_track+0x21/0x30
   __kasan_kmalloc+0x7a/0x90
   _smbd_get_connection+0x1b6f/0x2110
   smbd_get_connection+0x21/0x40
   cifs_get_tcp_session+0x8ef/0xda0
   mount_get_conns+0x60/0x750
   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

  Freed by task 824:
   kasan_save_stack+0x1e/0x40
   kasan_set_track+0x21/0x30
   kasan_save_free_info+0x2a/0x40
   ____kasan_slab_free+0x143/0x1b0
   __kmem_cache_free+0xc8/0x330
   _smbd_get_connection+0x1c6a/0x2110
   smbd_get_connection+0x21/0x40
   cifs_get_tcp_session+0x8ef/0xda0
   mount_get_conns+0x60/0x750
   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

Let's initialize the MR recovery work before MR allocate to prevent
the warning, remove the MRs from the list to prevent the UAF.

Fixes: c739858 ("CIFS: SMBD: Implement RDMA memory registration")
Acked-by: Paulo Alcantara (SUSE) <[email protected]>
Reviewed-by: Tom Talpey <[email protected]>
Signed-off-by: Zhang Xiaoxu <[email protected]>
Signed-off-by: Steve French <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

fs/cifs/smbdirect.c

@@ -2218,6 +2218,7 @@ static int allocate_mr_list(struct smbd_connection *info)
 	atomic_set(&info->mr_ready_count, 0);
 	atomic_set(&info->mr_used_count, 0);
 	init_waitqueue_head(&info->wait_for_mr_cleanup);
+	INIT_WORK(&info->mr_recovery_work, smbd_mr_recovery_work);
 	/* Allocate more MRs (2x) than hardware responder_resources */
 	for (i = 0; i < info->responder_resources * 2; i++) {
 		smbdirect_mr = kzalloc(sizeof(*smbdirect_mr), GFP_KERNEL);
@@ -2245,13 +2246,13 @@ static int allocate_mr_list(struct smbd_connection *info)
 		list_add_tail(&smbdirect_mr->list, &info->mr_list);
 		atomic_inc(&info->mr_ready_count);
 	}
-	INIT_WORK(&info->mr_recovery_work, smbd_mr_recovery_work);
 	return 0;
 
 out:
 	kfree(smbdirect_mr);
 
 	list_for_each_entry_safe(smbdirect_mr, tmp, &info->mr_list, list) {
+		list_del(&smbdirect_mr->list);
 		ib_dereg_mr(smbdirect_mr->mr);
 		kfree(smbdirect_mr->sgl);
 		kfree(smbdirect_mr);