CVE-2024-46796 smb: client: fix double put of @cfile in smb2_set_path_size()
In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix double put of @cfile in smb2_set_path_size()

If smb2_compound_op() is called with a valid @cfile and returned
-EINVAL, we need to call cifs_get_writable_path() before retrying it
as the reference of @cfile was already dropped by previous call.

This fixes the following KASAN splat when running fstests generic/013
against Windows Server 2022:

  CIFS: Attempting to mount //w22-fs0/scratch
  run fstests generic/013 at 2024-09-02 19:48:59
  ==================================================================
  BUG: KASAN: slab-use-after-free in detach_if_pending+0xab/0x200
  Write of size 8 at addr ffff88811f1a3730 by task kworker/3:2/176

  CPU: 3 UID: 0 PID: 176 Comm: kworker/3:2 Not tainted 6.11.0-rc6 #2
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40
  04/01/2014
  Workqueue: cifsoplockd cifs_oplock_break [cifs]
  Call Trace:
   <TASK>
   dump_stack_lvl+0x5d/0x80
   ? detach_if_pending+0xab/0x200
   print_report+0x156/0x4d9
   ? detach_if_pending+0xab/0x200
   ? __virt_addr_valid+0x145/0x300
   ? __phys_addr+0x46/0x90
   ? detach_if_pending+0xab/0x200
   kasan_report+0xda/0x110
   ? detach_if_pending+0xab/0x200
   detach_if_pending+0xab/0x200
   timer_delete+0x96/0xe0
   ? __pfx_timer_delete+0x10/0x10
   ? rcu_is_watching+0x20/0x50
   try_to_grab_pending+0x46/0x3b0
   __cancel_work+0x89/0x1b0
   ? __pfx___cancel_work+0x10/0x10
   ? kasan_save_track+0x14/0x30
   cifs_close_deferred_file+0x110/0x2c0 [cifs]
   ? __pfx_cifs_close_deferred_file+0x10/0x10 [cifs]
   ? __pfx_down_read+0x10/0x10
   cifs_oplock_break+0x4c1/0xa50 [cifs]
   ? __pfx_cifs_oplock_break+0x10/0x10 [cifs]
   ? lock_is_held_type+0x85/0xf0
   ? mark_held_locks+0x1a/0x90
   process_one_work+0x4c6/0x9f0
   ? find_held_lock+0x8a/0xa0
   ? __pfx_process_one_work+0x10/0x10
   ? lock_acquired+0x220/0x550
   ? __list_add_valid_or_report+0x37/0x100
   worker_thread+0x2e4/0x570
   ? __kthread_parkme+0xd1/0xf0
   ? __pfx_worker_thread+0x10/0x10
   kthread+0x17f/0x1c0
   ? kthread+0xda/0x1c0
   ? __pfx_kthread+0x10/0x10
   ret_from_fork+0x31/0x60
   ? __pfx_kthread+0x10/0x10
   ret_from_fork_asm+0x1a/0x30
   </TASK>

  Allocated by task 1118:
   kasan_save_stack+0x30/0x50
   kasan_save_track+0x14/0x30
   __kasan_kmalloc+0xaa/0xb0
   cifs_new_fileinfo+0xc8/0x9d0 [cifs]
   cifs_atomic_open+0x467/0x770 [cifs]
   lookup_open.isra.0+0x665/0x8b0
   path_openat+0x4c3/0x1380
   do_filp_open+0x167/0x270
   do_sys_openat2+0x129/0x160
   __x64_sys_creat+0xad/0xe0
   do_syscall_64+0xbb/0x1d0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

  Freed by task 83:
   kasan_save_stack+0x30/0x50
   kasan_save_track+0x14/0x30
   kasan_save_free_info+0x3b/0x70
   poison_slab_object+0xe9/0x160
   __kasan_slab_free+0x32/0x50
   kfree+0xf2/0x300
   process_one_work+0x4c6/0x9f0
   worker_thread+0x2e4/0x570
   kthread+0x17f/0x1c0
   ret_from_fork+0x31/0x60
   ret_from_fork_asm+0x1a/0x30

  Last potentially related work creation:
   kasan_save_stack+0x30/0x50
   __kasan_record_aux_stack+0xad/0xc0
   insert_work+0x29/0xe0
   __queue_work+0x5ea/0x760
   queue_work_on+0x6d/0x90
   _cifsFileInfo_put+0x3f6/0x770 [cifs]
   smb2_compound_op+0x911/0x3940 [cifs]
   smb2_set_path_size+0x228/0x270 [cifs]
   cifs_set_file_size+0x197/0x460 [cifs]
   cifs_setattr+0xd9c/0x14b0 [cifs]
   notify_change+0x4e3/0x740
   do_truncate+0xfa/0x180
   vfs_truncate+0x195/0x200
   __x64_sys_truncate+0x109/0x150
   do_syscall_64+0xbb/0x1d0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
Affected products: vendor: Linux
product: Linux
default_status: unaffected
vendor: Linux
product: Linux
default_status: affected
Published: 2024-09-18T07:12:51.038Z