Subject: CVE-2023-52741: cifs: Fix use-after-free in rdata->read_into_pages()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

cifs: Fix use-after-free in rdata->read_into_pages()

When the network status is unstable, use-after-free may occur when
read data from the server.

  BUG: KASAN: use-after-free in readpages_fill_pages+0x14c/0x7e0

  Call Trace:
   <TASK>
   dump_stack_lvl+0x38/0x4c
   print_report+0x16f/0x4a6
   kasan_report+0xb7/0x130
   readpages_fill_pages+0x14c/0x7e0
   cifs_readv_receive+0x46d/0xa40
   cifs_demultiplex_thread+0x121c/0x1490
   kthread+0x16b/0x1a0
   ret_from_fork+0x2c/0x50
   </TASK>

  Allocated by task 2535:
   kasan_save_stack+0x22/0x50
   kasan_set_track+0x25/0x30
   __kasan_kmalloc+0x82/0x90
   cifs_readdata_direct_alloc+0x2c/0x110
   cifs_readdata_alloc+0x2d/0x60
   cifs_readahead+0x393/0xfe0
   read_pages+0x12f/0x470
   page_cache_ra_unbounded+0x1b1/0x240
   filemap_get_pages+0x1c8/0x9a0
   filemap_read+0x1c0/0x540
   cifs_strict_readv+0x21b/0x240
   vfs_read+0x395/0x4b0
   ksys_read+0xb8/0x150
   do_syscall_64+0x3f/0x90
   entry_SYSCALL_64_after_hwframe+0x72/0xdc

  Freed by task 79:
   kasan_save_stack+0x22/0x50
   kasan_set_track+0x25/0x30
   kasan_save_free_info+0x2e/0x50
   __kasan_slab_free+0x10e/0x1a0
   __kmem_cache_free+0x7a/0x1a0
   cifs_readdata_release+0x49/0x60
   process_one_work+0x46c/0x760
   worker_thread+0x2a4/0x6f0
   kthread+0x16b/0x1a0
   ret_from_fork+0x2c/0x50

  Last potentially related work creation:
   kasan_save_stack+0x22/0x50
   __kasan_record_aux_stack+0x95/0xb0
   insert_work+0x2b/0x130
   __queue_work+0x1fe/0x660
   queue_work_on+0x4b/0x60
   smb2_readv_callback+0x396/0x800
   cifs_abort_connection+0x474/0x6a0
   cifs_reconnect+0x5cb/0xa50
   cifs_readv_from_socket.cold+0x22/0x6c
   cifs_read_page_from_socket+0xc1/0x100
   readpages_fill_pages.cold+0x2f/0x46
   cifs_readv_receive+0x46d/0xa40
   cifs_demultiplex_thread+0x121c/0x1490
   kthread+0x16b/0x1a0
   ret_from_fork+0x2c/0x50

The following function calls will cause UAF of the rdata pointer.

readpages_fill_pages
 cifs_read_page_from_socket
  cifs_readv_from_socket
   cifs_reconnect
    __cifs_reconnect
     cifs_abort_connection
      mid->callback() --> smb2_readv_callback
       queue_work(&rdata->work)  # if the worker completes first,
                                 # the rdata is freed
          cifs_readv_complete
            kref_put
              cifs_readdata_release
                kfree(rdata)
 return rdata->...               # UAF in readpages_fill_pages()

Similarly, this problem also occurs in the uncache_fill_pages().

Fix this by adjusts the order of condition judgment in the return
statement.

The Linux kernel CVE team has assigned CVE-2023-52741 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.10.168 with commit 2b693fe3f760
	Fixed in 5.15.94 with commit d1fba1e096ff
	Fixed in 6.1.12 with commit 3684a2f6affa
	Fixed in 6.2 with commit aa5465aeca3c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-52741
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/cifs/file.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2b693fe3f760c87fd9768e759f6297f743a1b3b0
	https://git.kernel.org/stable/c/d1fba1e096ffc7ec11df863a97c50203c47315b9
	https://git.kernel.org/stable/c/3684a2f6affa1ca52a5d4a12f04d0652efdee65e
	https://git.kernel.org/stable/c/aa5465aeca3c66fecdf7efcf554aed79b4c4b211