From: Vincent Whitchurch vincent.whitchurch@axis.com
stable inclusion from linux-4.19.183 commit b0834edc70e402244ed8da96664368c15d869582
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commit 05946d4b7a7349ae58bfa2d51ae832e64a394c2d upstream.
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 [aaptel: backport to kernel without CIFS_SESS_OP and multichannel] Signed-off-by: Aurelien Aptel aaptel@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- 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 70412944b267..59643acb6d67 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -891,9 +891,12 @@ 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(&ses->server->srv_mutex); smb311_update_preauth_hash(ses, rqst[0].rq_iov, rqst[0].rq_nvec); + mutex_unlock(&ses->server->srv_mutex); + }
if (timeout == CIFS_ASYNC_OP) goto out; @@ -964,7 +967,9 @@ 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(&ses->server->srv_mutex); smb311_update_preauth_hash(ses, &iov, 1); + mutex_unlock(&ses->server->srv_mutex); }
out: