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authorJan Beulich <jbeulich@suse.com>2021-02-15 10:56:44 +0300
committerJuergen Gross <jgross@suse.com>2021-02-15 10:56:44 +0300
commit871997bc9e423f05c7da7c9178e62dde5df2a7f8 (patch)
tree31bdf5ee41af83e487cd234fa7b947e5c9165a8b /drivers/block/xen-blkback
parent7c77474b2d22176d2bfb592ec74e0f2cb71352c9 (diff)
downloadlinux-871997bc9e423f05c7da7c9178e62dde5df2a7f8.tar.xz
xen-blkback: fix error handling in xen_blkbk_map()
The function uses a goto-based loop, which may lead to an earlier error getting discarded by a later iteration. Exit this ad-hoc loop when an error was encountered. The out-of-memory error path additionally fails to fill a structure field looked at by xen_blkbk_unmap_prepare() before inspecting the handle which does get properly set (to BLKBACK_INVALID_HANDLE). Since the earlier exiting from the ad-hoc loop requires the same field filling (invalidation) as that on the out-of-memory path, fold both paths. While doing so, drop the pr_alert(), as extra log messages aren't going to help the situation (the kernel will log oom conditions already anyway). This is XSA-365. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Julien Grall <julien@xen.org> Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/block/xen-blkback')
-rw-r--r--drivers/block/xen-blkback/blkback.c26
1 files changed, 16 insertions, 10 deletions
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index ee62b3c0b55a..da16121140ca 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -794,8 +794,13 @@ again:
pages[i]->persistent_gnt = persistent_gnt;
} else {
if (gnttab_page_cache_get(&ring->free_pages,
- &pages[i]->page))
- goto out_of_memory;
+ &pages[i]->page)) {
+ gnttab_page_cache_put(&ring->free_pages,
+ pages_to_gnt,
+ segs_to_map);
+ ret = -ENOMEM;
+ goto out;
+ }
addr = vaddr(pages[i]->page);
pages_to_gnt[segs_to_map] = pages[i]->page;
pages[i]->persistent_gnt = NULL;
@@ -880,17 +885,18 @@ next:
}
segs_to_map = 0;
last_map = map_until;
- if (map_until != num)
+ if (!ret && map_until != num)
goto again;
- return ret;
-
-out_of_memory:
- pr_alert("%s: out of memory\n", __func__);
- gnttab_page_cache_put(&ring->free_pages, pages_to_gnt, segs_to_map);
- for (i = last_map; i < num; i++)
+out:
+ for (i = last_map; i < num; i++) {
+ /* Don't zap current batch's valid persistent grants. */
+ if(i >= last_map + segs_to_map)
+ pages[i]->persistent_gnt = NULL;
pages[i]->handle = BLKBACK_INVALID_HANDLE;
- return -ENOMEM;
+ }
+
+ return ret;
}
static int xen_blkbk_map_seg(struct pending_req *pending_req)