Commit d3f92988 authored by Jan Beulich's avatar Jan Beulich Committed by Zheng Zengkai
Browse files

xen-blkback: fix error handling in xen_blkbk_map() 



stable inclusion
from stable-5.10.18
commit 00805af45a21729e2901a37914992786a0d32c46
bugzilla: 50148

--------------------------------

commit 871997bc upstream.

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: default avatarJan Beulich <jbeulich@suse.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarJulien Grall <julien@xen.org>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: default avatarChen Jun <chenjun102@huawei.com>
Acked-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
parent 987621a6

drivers/block/xen-blkback/blkback.c

+16 −10
Original line number Diff line number Diff line
@@ -794,8 +794,13 @@ static int xen_blkbk_map(struct xen_blkif_ring *ring, 
			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 @@ static int xen_blkbk_map(struct xen_blkif_ring *ring, 
	}

	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)