smb: client: fix use-after-free bug in cifs_debug_data_proc_show()

Skip SMB sessions that are being teared down
(e.g. @ses->ses_status == SES_EXITING) in cifs_debug_data_proc_show()
to avoid use-after-free in @ses.

This fixes the following GPF when reading from /proc/fs/cifs/DebugData
while mounting and umounting

  [ 816.251274] general protection fault, probably for non-canonical
  address 0x6b6b6b6b6b6b6d81: 0000 [#1] PREEMPT SMP NOPTI
  ...
  [  816.260138] Call Trace:
  [  816.260329]  <TASK>
  [  816.260499]  ? die_addr+0x36/0x90
  [  816.260762]  ? exc_general_protection+0x1b3/0x410
  [  816.261126]  ? asm_exc_general_protection+0x26/0x30
  [  816.261502]  ? cifs_debug_tcon+0xbd/0x240 [cifs]
  [  816.261878]  ? cifs_debug_tcon+0xab/0x240 [cifs]
  [  816.262249]  cifs_debug_data_proc_show+0x516/0xdb0 [cifs]
  [  816.262689]  ? seq_read_iter+0x379/0x470
  [  816.262995]  seq_read_iter+0x118/0x470
  [  816.263291]  proc_reg_read_iter+0x53/0x90
  [  816.263596]  ? srso_alias_return_thunk+0x5/0x7f
  [  816.263945]  vfs_read+0x201/0x350
  [  816.264211]  ksys_read+0x75/0x100
  [  816.264472]  do_syscall_64+0x3f/0x90
  [  816.264750]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
  [  816.265135] RIP: 0033:0x7fd5e669d381

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2023-10-24 13:49:15 -03:00 committed by Steve French
parent e6322fd177
commit d328c09ee9

View File

@ -452,6 +452,11 @@ skip_rdma:
seq_printf(m, "\n\n\tSessions: ");
i = 0;
list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
spin_lock(&ses->ses_lock);
if (ses->ses_status == SES_EXITING) {
spin_unlock(&ses->ses_lock);
continue;
}
i++;
if ((ses->serverDomain == NULL) ||
(ses->serverOS == NULL) ||
@ -472,6 +477,7 @@ skip_rdma:
ses->ses_count, ses->serverOS, ses->serverNOS,
ses->capabilities, ses->ses_status);
}
spin_unlock(&ses->ses_lock);
seq_printf(m, "\n\tSecurity type: %s ",
get_security_type_str(server->ops->select_sectype(server, ses->sectype)));