tree bf71012883b3f26048c505a926d9ef5d43b37f8c
parent f5aa58413914690503cd390483df4c040b1e294f
author Juergen Gross <jgross@suse.com> 1638187926 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1638949504 +0100

xen/blkfront: don't trust the backend response data blindly

commit b94e4b147fd1992ad450e1fea1fdaa3738753373 upstream.

Today blkfront will trust the backend to send only sane response data.
In order to avoid privilege escalations or crashes in case of malicious
backends verify the data to be within expected limits. Especially make
sure that the response always references an outstanding request.

Introduce a new state of the ring BLKIF_STATE_ERROR which will be
switched to in case an inconsistency is being detected. Recovering from
this state is possible only via removing and adding the virtual device
again (e.g. via a suspend/resume cycle).

Make all warning messages issued due to valid error responses rate
limited in order to avoid message floods being triggered by a malicious
backend.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20210730103854.12681-4-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>