From 0647d47cc184da587c76743546b6af6dfdb8f1da Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 13 Sep 2016 09:56:27 +0100 Subject: [PATCH] qcow2: avoid memcpy(dst, NULL, len) Section "7.1.4 Use of library functions" in the C99 standard says: If an argument to a function has an invalid value (such as [...] a null pointer [...]) [...] the behavior is undefined. Additionally the "searching and sorting" functions are specified as requiring valid pointer values as described in 7.1.4. This patch fixes the following sanitizer errors: block/qcow2.c:1807:41: runtime error: null pointer passed as argument 2, which is declared to never be null block/qcow2-cluster.c:86:26: runtime error: null pointer passed as argument 2, which is declared to never be null Reported-by: Peter Maydell Reviewed-by: Kevin Wolf Message-id: 1473758138-19260-1-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- block/qcow2-cluster.c | 4 +++- block/qcow2.c | 5 ++++- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index f94183529c..9ab445dd17 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -83,7 +83,9 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, } memset(new_l1_table, 0, align_offset(new_l1_size2, 512)); - memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t)); + if (s->l1_size) { + memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t)); + } /* write new table (align to cluster) */ BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE); diff --git a/block/qcow2.c b/block/qcow2.c index c079aa83b6..0e53a4d666 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1804,7 +1804,10 @@ static size_t header_ext_add(char *buf, uint32_t magic, const void *s, .magic = cpu_to_be32(magic), .len = cpu_to_be32(len), }; - memcpy(buf + sizeof(QCowExtension), s, len); + + if (len) { + memcpy(buf + sizeof(QCowExtension), s, len); + } return ext_len; }