[dpdk-dev] [PATCH] malloc: fix potential null pointer dereference

[Tiwei Bie <tiwei.bie@intel.com>]

We need to do the NULL pointer check first after malloc().

Fixes: 07dcbfe0101f ("malloc: support multiprocess memory hotplug")
Cc: stable@dpdk.org

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 lib/librte_eal/common/malloc_heap.c | 4 +---
 lib/librte_eal/common/malloc_mp.c   | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/librte_eal/common/malloc_heap.c b/lib/librte_eal/common/malloc_heap.c
index 12aaf2d72..ac7bbb3ba 100644
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -326,11 +326,9 @@ try_expand_heap_primary(struct malloc_heap *heap, uint64_t pg_sz,
 
 	/* we can't know in advance how many pages we'll need, so we malloc */
 	ms = malloc(sizeof(*ms) * n_segs);
-
-	memset(ms, 0, sizeof(*ms) * n_segs);
-
 	if (ms == NULL)
 		return -1;
+	memset(ms, 0, sizeof(*ms) * n_segs);
 
 	elem = alloc_pages_on_heap(heap, pg_sz, elt_size, socket, flags, align,
 			bound, contig, ms, n_segs);
diff --git a/lib/librte_eal/common/malloc_mp.c b/lib/librte_eal/common/malloc_mp.c
index 931c14bc5..5f2d4e0be 100644
--- a/lib/librte_eal/common/malloc_mp.c
+++ b/lib/librte_eal/common/malloc_mp.c
@@ -194,13 +194,11 @@ handle_alloc_request(const struct malloc_mp_req *m,
 
 	/* we can't know in advance how many pages we'll need, so we malloc */
 	ms = malloc(sizeof(*ms) * n_segs);
-
-	memset(ms, 0, sizeof(*ms) * n_segs);
-
 	if (ms == NULL) {
 		RTE_LOG(ERR, EAL, "Couldn't allocate memory for request state\n");
 		goto fail;
 	}
+	memset(ms, 0, sizeof(*ms) * n_segs);
 
 	elem = alloc_pages_on_heap(heap, ar->page_sz, ar->elt_size, ar->socket,
 			ar->flags, ar->align, ar->bound, ar->contig, ms,
-- 
2.18.0