When shutting down the server in cifs_put_tcp_session(), cifsd thread
might be reconnecting to multiple DFS targets before it realizes it
should exit the loop, so we can't free @server->hostname as long as
cifsd tread is done. Otherwise the following can happen:
RIP: 0010:__slab_free+0x223/0x3c0
Code: 5e 41 5f c3 cc cc cc cc 4c 89 de 4c 89 cf 44 89 44 24 08 4c 89
1c 24 e8 fb cf 8e 00 44 8b 44 24 08 4c 8b 1c 24 e9 5f fe ff ff <0f>
0b 41 f7 45 08 00 0d 21 00 0f 85 2d ff ff ff e9 1f ff ff ff 80
RSP: 0018:ffffb26180dbfd08 EFLAGS: 00010246
RAX: ffff8ea34728e510 RBX: ffff8ea34728e500 RCX: 0000000000800068
RDX: 0000000000800068 RSI: 0000000000000000 RDI: ffff8ea340042400
RBP: ffffe112041ca380 R08: 0000000000000001 R09: 0000000000000000
R10: 6170732e31303000 R11: 70726f632e786563 R12: ffff8ea34728e500
R13: ffff8ea340042400 R14: ffff8ea34728e500 R15: 0000000000800068
FS: 0000000000000000(0000) GS:ffff8ea66fd80000(0000)
000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc25376080 CR3: 000000012a2ba001 CR4:
PKRU: 55555554
Call Trace:
<TASK>
? show_trace_log_lvl+0x1c4/0x2df
? show_trace_log_lvl+0x1c4/0x2df
? __reconnect_target_unlocked+0x3e/0x160 [cifs]
? __die_body.cold+0x8/0xd
? die+0x2b/0x50
? do_trap+0xce/0x120
? __slab_free+0x223/0x3c0
? do_error_trap+0x65/0x80
? __slab_free+0x223/0x3c0
? exc_invalid_op+0x4e/0x70
? __slab_free+0x223/0x3c0
? asm_exc_invalid_op+0x16/0x20
? __slab_free+0x223/0x3c0
? extract_hostname+0x5c/0xa0 [cifs]
? extract_hostname+0x5c/0xa0 [cifs]
? __kmalloc+0x4b/0x140
__reconnect_target_unlocked+0x3e/0x160 [cifs]
reconnect_dfs_server+0x145/0x430 [cifs]
cifs_handle_standard+0x1ad/0x1d0 [cifs]
cifs_demultiplex_thread+0x592/0x730 [cifs]
? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
kthread+0xdd/0x100
? __pfx_kthread+0x10/0x10
ret_from_fork+0x29/0x50
</TASK>
Fixes: 7be3248f3139 ("cifs: To match file servers, make sure the server hostname matches")
Reported-by: Jay Shin <jaeshin@xxxxxxxxxx>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@xxxxxxxxxxxxx>
---
fs/smb/client/connect.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index ddcc9e514a0e..eaa6be4456d0 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -1044,6 +1044,7 @@ clean_demultiplex_info(struct TCP_Server_Info *server)
/* Release netns reference for this server. */
put_net(cifs_net_ns(server));
kfree(server->leaf_fullpath);
+ kfree(server->hostname);
kfree(server);
length = atomic_dec_return(&tcpSesAllocCount);
@@ -1670,8 +1671,6 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
kfree_sensitive(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;
- kfree(server->hostname);
- server->hostname = NULL;
task = xchg(&server->tsk, NULL);
if (task)
--
2.47.1
