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block/iscsi: avoid data corruption with cache=writeback

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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 <pl@kamp.de>
Message-Id: <1484579832-18589-1-git-send-email-pl@kamp.de>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Lieven 2017-01-16 16:17:12 +01:00 committed by Paolo Bonzini
parent b8bab8eb69
commit 1da45e0c4c
1 changed files with 6 additions and 2 deletions
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8
block/iscsi.c
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@ -499,14 +499,18 @@ iscsi_allocmap_update(IscsiLun *iscsilun, int64_t sector_num,
if (allocated) { if (allocated) {
bitmap_set(iscsilun->allocmap, cl_num_expanded, nb_cls_expanded); bitmap_set(iscsilun->allocmap, cl_num_expanded, nb_cls_expanded);
} else { } 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) { if (iscsilun->allocmap_valid == NULL) {
return; return;
} }
if (valid) { 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 { } else {
bitmap_clear(iscsilun->allocmap_valid, cl_num_expanded, bitmap_clear(iscsilun->allocmap_valid, cl_num_expanded,
nb_cls_expanded); nb_cls_expanded);