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| author | Eric Blake <eblake@redhat.com> | 2021-11-15 16:39:43 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2021-11-16 08:45:33 -0600 |
| commit | 76df2b8d695b07d85cce7db753a51cdbfe42b445 (patch) | |
| tree | da39022ad64309a3148f6a2931085ea78366f04c /nbd | |
| parent | 9f0f846465d4c52ce9857787e947dffb64367fae (diff) | |
| download | qemu-76df2b8d695b07d85cce7db753a51cdbfe42b445.zip qemu-76df2b8d695b07d85cce7db753a51cdbfe42b445.tar.gz qemu-76df2b8d695b07d85cce7db753a51cdbfe42b445.tar.bz2 | |
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.c | 13 |
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); |