diff options
| author | Juergen Gross <jgross@suse.com> | 2022-03-07 09:48:54 +0100 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2022-03-07 09:48:54 +0100 |
| commit | 31185df7e2b1d2fa1de4900247a12d7b9c7087eb (patch) | |
| tree | da3daf6834b4aed5d6ea01feb1ec934a0488dc9b /drivers/net/xen-netfront.c | |
| parent | abf1fd5919d6238ee3bc5eb4a9b6c3947caa6638 (diff) | |
xen/netfront: don't use gnttab_query_foreign_access() for mapped status
It isn't enough to check whether a grant is still being in use by
calling gnttab_query_foreign_access(), as a mapping could be realized
by the other side just after having called that function.
In case the call was done in preparation of revoking a grant it is
better to do so via gnttab_end_foreign_access_ref() and check the
success of that operation instead.
This is CVE-2022-23037 / part of XSA-396.
Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
V2:
- use gnttab_try_end_foreign_access()
V3:
- don't use gnttab_try_end_foreign_access()
Diffstat (limited to 'drivers/net/xen-netfront.c')
| -rw-r--r-- | drivers/net/xen-netfront.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 7748f07e2cf1..13926d03418e 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -424,14 +424,12 @@ static bool xennet_tx_buf_gc(struct netfront_queue *queue) queue->tx_link[id] = TX_LINK_NONE; skb = queue->tx_skbs[id]; queue->tx_skbs[id] = NULL; - if (unlikely(gnttab_query_foreign_access( - queue->grant_tx_ref[id]) != 0)) { + if (unlikely(!gnttab_end_foreign_access_ref( + queue->grant_tx_ref[id], GNTMAP_readonly))) { dev_alert(dev, "Grant still in use by backend domain\n"); goto err; } - gnttab_end_foreign_access_ref( - queue->grant_tx_ref[id], GNTMAP_readonly); gnttab_release_grant_reference( &queue->gref_tx_head, queue->grant_tx_ref[id]); queue->grant_tx_ref[id] = GRANT_INVALID_REF; |