Hi Greg,
<gregkh@xxxxxxxxxxxxxxxxxxx> writes:
> The patch below does not apply to the 5.11-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
This should apply to 5.11, 5.10 and 5.4.
> From 05946d4b7a7349ae58bfa2d51ae832e64a394c2d Mon Sep 17 00:00:00 2001
>From 1d225f77208b58f6a81d6038964caad2dd637443 Mon Sep 17 00:00:00 2001
From: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
Date: Wed, 10 Mar 2021 13:20:40 +0100
Subject: [PATCH] cifs: Fix preauth hash corruption
smb311_update_preauth_hash() uses the shash in server->secmech without
appropriate locking, and this can lead to sessions corrupting each
other's preauth hashes.
The following script can easily trigger the problem:
#!/bin/sh -e
NMOUNTS=10
for i in $(seq $NMOUNTS);
mkdir -p /tmp/mnt$i
umount /tmp/mnt$i 2>/dev/null || :
done
while :; do
for i in $(seq $NMOUNTS); do
mount -t cifs //192.168.0.1/test /tmp/mnt$i -o ... &
done
wait
for i in $(seq $NMOUNTS); do
umount /tmp/mnt$i
done
done
Usually within seconds this leads to one or more of the mounts failing
with the following errors, and a "Bad SMB2 signature for message" is
seen in the server logs:
CIFS: VFS: \\192.168.0.1 failed to connect to IPC (rc=-13)
CIFS: VFS: cifs_mount failed w/return code = -13
Fix it by holding the server mutex just like in the other places where
the shashes are used.
Fixes: 8bd68c6e47abff34e4 ("CIFS: implement v3.11 preauth integrity")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
[aaptel: backport to kernel without CIFS_SESS_OP]
Signed-off-by: Aurelien Aptel <aaptel@xxxxxxxx>
---
fs/cifs/transport.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 14ecf1a9f11a..64fccb8809ec 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -1171,9 +1171,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
/*
* Compounding is never used during session establish.
*/
- if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP))
+ if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP)) {
+ mutex_lock(&server->srv_mutex);
smb311_update_preauth_hash(ses, rqst[0].rq_iov,
rqst[0].rq_nvec);
+ mutex_unlock(&server->srv_mutex);
+ }
for (i = 0; i < num_rqst; i++) {
rc = wait_for_response(server, midQ[i]);
@@ -1241,7 +1244,9 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
.iov_base = resp_iov[0].iov_base,
.iov_len = resp_iov[0].iov_len
};
+ mutex_lock(&server->srv_mutex);
smb311_update_preauth_hash(ses, &iov, 1);
+ mutex_unlock(&server->srv_mutex);
}
out:
--
2.30.0
Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
