From 1da45e0c4cf4719fa75898d019e0874b9b2bc774 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Mon, 16 Jan 2017 16:17:12 +0100 Subject: block/iscsi: avoid data corruption with cache=writeback nb_cls_shrunk in iscsi_allocmap_update can become -1 if the request starts and ends within the same cluster. This results in passing -1 to bitmap_set and bitmap_clear and they don't handle negative values properly. In the end this leads to data corruption. Fixes: e1123a3b40a1a9a625a29c8ed4debb7e206ea690 Cc: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Message-Id: <1484579832-18589-1-git-send-email-pl@kamp.de> Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- block/iscsi.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'block/iscsi.c') diff --git a/block/iscsi.c b/block/iscsi.c index 6aeeb9ec4f..1860f1bc91 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -499,14 +499,18 @@ iscsi_allocmap_update(IscsiLun *iscsilun, int64_t sector_num, if (allocated) { bitmap_set(iscsilun->allocmap, cl_num_expanded, nb_cls_expanded); } else { - bitmap_clear(iscsilun->allocmap, cl_num_shrunk, nb_cls_shrunk); + if (nb_cls_shrunk > 0) { + bitmap_clear(iscsilun->allocmap, cl_num_shrunk, nb_cls_shrunk); + } } if (iscsilun->allocmap_valid == NULL) { return; } if (valid) { - bitmap_set(iscsilun->allocmap_valid, cl_num_shrunk, nb_cls_shrunk); + if (nb_cls_shrunk > 0) { + bitmap_set(iscsilun->allocmap_valid, cl_num_shrunk, nb_cls_shrunk); + } } else { bitmap_clear(iscsilun->allocmap_valid, cl_num_expanded, nb_cls_expanded); -- cgit v1.2.1