From e9de2e5fd602c4f5ddf212d3837b19ad4f5878ad Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Tue, 2 Sep 2014 15:21:29 +0100 Subject: [PATCH] xen/gntalloc: fix oops after runnning out of grant refs Only set gref->gref_id if foreign access was successfully granted and the grant ref is valid. If gref->gref_id == -ENOSPC the test in __del_gref() would incorrectly attempt to end foreign access (because grant_ref_t is unsigned). Signed-off-by: David Vrabel Reported-by: Dave Scott Reviewed-by: Boris Ostrovsky --- drivers/xen/gntalloc.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c index 787d17945418..8ed2bb4f6f21 100644 --- a/drivers/xen/gntalloc.c +++ b/drivers/xen/gntalloc.c @@ -141,13 +141,11 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op, goto undo; /* Grant foreign access to the page. */ - gref->gref_id = gnttab_grant_foreign_access(op->domid, + rc = gnttab_grant_foreign_access(op->domid, pfn_to_mfn(page_to_pfn(gref->page)), readonly); - if ((int)gref->gref_id < 0) { - rc = gref->gref_id; + if (rc < 0) goto undo; - } - gref_ids[i] = gref->gref_id; + gref_ids[i] = gref->gref_id = rc; } /* Add to gref lists. */ @@ -193,7 +191,7 @@ static void __del_gref(struct gntalloc_gref *gref) gref->notify.flags = 0; - if (gref->gref_id > 0) { + if (gref->gref_id) { if (gnttab_query_foreign_access(gref->gref_id)) return;