diff options
| author | Vincent Whitchurch <vincent.whitchurch@axis.com> | 2021-03-10 15:20:40 +0300 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2021-03-15 02:14:32 +0300 |
| commit | 05946d4b7a7349ae58bfa2d51ae832e64a394c2d (patch) | |
| tree | f85ea7afc996d117fb97593feca7df8fe36dbde7 | |
| parent | 5171317dfd9afcf729799d31fffdbb9e71e45402 (diff) | |
| download | linux-05946d4b7a7349ae58bfa2d51ae832e64a394c2d.tar.xz | |
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@axis.com>
CC: <stable@vger.kernel.org>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
| -rw-r--r-- | fs/cifs/transport.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 007d99437c77..c1725b55f364 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -1196,9 +1196,12 @@ 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) || (optype & CIFS_SESS_OP)) + if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_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]); @@ -1266,7 +1269,9 @@ 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: |