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authorEric Blake <eblake@redhat.com>2021-11-15 16:39:43 -0600
committerEric Blake <eblake@redhat.com>2021-11-16 08:45:33 -0600
commit76df2b8d695b07d85cce7db753a51cdbfe42b445 (patch)
treeda39022ad64309a3148f6a2931085ea78366f04c /nbd
parent9f0f846465d4c52ce9857787e947dffb64367fae (diff)
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nbd/server: Silence clang sanitizer warning
clang's sanitizer is picky: memset(NULL, x, 0) is technically undefined behavior, even though no sane implementation of memset() deferences the NULL. Caught by the nbd-qemu-allocation iotest. The alternative to checking before each memset is to instead force an allocation of 1 element instead of g_new0(type, 0)'s behavior of returning NULL for a 0-length array. Reported-by: Peter Maydell <peter.maydell@linaro.org> Fixes: 3b1f244c59 (nbd: Allow export of multiple bitmaps for one device) Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20211115223943.626416-1-eblake@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Diffstat (limited to 'nbd')
-rw-r--r--nbd/server.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/nbd/server.c b/nbd/server.c
index 6d03e8a..d9164ee 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2016-2020 Red Hat, Inc.
+ * Copyright (C) 2016-2021 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Server Side
@@ -879,7 +879,9 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,
if (!*query) {
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
meta->allocation_depth = meta->exp->allocation_depth;
- memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
+ if (meta->exp->nr_export_bitmaps) {
+ memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
+ }
}
trace_nbd_negotiate_meta_query_parse("empty");
return true;
@@ -894,7 +896,8 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,
if (nbd_strshift(&query, "dirty-bitmap:")) {
trace_nbd_negotiate_meta_query_parse("dirty-bitmap:");
if (!*query) {
- if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
+ if (client->opt == NBD_OPT_LIST_META_CONTEXT &&
+ meta->exp->nr_export_bitmaps) {
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
}
trace_nbd_negotiate_meta_query_parse("empty");
@@ -1024,7 +1027,9 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
/* enable all known contexts */
meta->base_allocation = true;
meta->allocation_depth = meta->exp->allocation_depth;
- memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
+ if (meta->exp->nr_export_bitmaps) {
+ memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
+ }
} else {
for (i = 0; i < nb_queries; ++i) {
ret = nbd_negotiate_meta_query(client, meta, errp);