| Message ID | 20210310122040.17515-1-vincent.whitchurch@axis.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | cifs: Fix preauth hash corruption | expand |
Good catch, thanks Vincent.
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Cheers,
cc: stable? On Wed, Mar 10, 2021 at 6:21 AM Vincent Whitchurch <vincent.whitchurch@axis.com> wrote: > > 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> > --- > 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 e90a1d1380b0..aa9c0f6bc263 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: > -- > 2.28.0 >
Steve French <smfrench@gmail.com> writes:
> cc: stable?
Sounds good
Cheers,
Thanks for the patch! Agree with a stable tag. -- Best regards, Pavel Shilovsky чт, 11 мар. 2021 г. в 02:01, Aurélien Aptel <aaptel@suse.com>: > > Steve French <smfrench@gmail.com> writes: > > cc: stable? > > Sounds good > > 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) >
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index e90a1d1380b0..aa9c0f6bc263 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:
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> --- fs/cifs/transport.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)