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

[Tiwei Bie]

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

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

Signed-off-by: Tiwei Bie <tiwei....@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