[PATCH nftables] src: add xzalloc_array() and use it to allocate the expression hashtable

[PATCH nftables] src: add xzalloc_array() and use it to allocate the expression hashtable

[Pablo Neira Ayuso]

Otherwise, assertion to ensure that no colission occur is hit due to
uninitialized hashtable memory area:

nft: netlink_delinearize.c:1741: expr_handler_init: Assertion `expr_handle_ht[hash] == NULL' failed.

Fixes: c4058f96c6a5 ("netlink_delinearize: Fix suspicious calloc() call")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/utils.h           |  1 +
 src/netlink_delinearize.c |  2 +-
 src/utils.c               | 10 ++++++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/utils.h b/include/utils.h
index f45f25132d18..ffbe2cbb75be 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -133,6 +133,7 @@ extern void *xmalloc(size_t size);
 extern void *xmalloc_array(size_t nmemb, size_t size);
 extern void *xrealloc(void *ptr, size_t size);
 extern void *xzalloc(size_t size);
+extern void *xzalloc_array(size_t nmemb, size_t size);
 extern char *xstrdup(const char *s);
 extern void xstrunescape(const char *in, char *out);
 
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 9a1cf3c4f7d9..57af71a75609 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -1733,7 +1733,7 @@ void expr_handler_init(void)
 	unsigned int i;
 	uint32_t hash;
 
-	expr_handle_ht = xmalloc_array(NFT_EXPR_HSIZE,
+	expr_handle_ht = xzalloc_array(NFT_EXPR_HSIZE,
 				       sizeof(expr_handle_ht[0]));
 
 	for (i = 0; i < array_size(netlink_parsers); i++) {
diff --git a/src/utils.c b/src/utils.c
index 47f5b791547b..925841c571f5 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -50,6 +50,16 @@ void *xmalloc_array(size_t nmemb, size_t size)
 	return xmalloc(nmemb * size);
 }
 
+void *xzalloc_array(size_t nmemb, size_t size)
+{
+	void *ptr;
+
+	ptr = xmalloc_array(nmemb, size);
+	memset(ptr, 0, nmemb * size);
+
+	return ptr;
+}
+
 void *xrealloc(void *ptr, size_t size)
 {
 	ptr = realloc(ptr, size);
-- 
2.30.2

Re: [PATCH nftables] src: add xzalloc_array() and use it to allocate the expression hashtable

[Phil Sutter]

On Mon, Jun 14, 2021 at 02:50:56PM +0200, Pablo Neira Ayuso wrote:
> Otherwise, assertion to ensure that no colission occur is hit due to
> uninitialized hashtable memory area:
> 
> nft: netlink_delinearize.c:1741: expr_handler_init: Assertion `expr_handle_ht[hash] == NULL' failed.

Oh, stupid mistake. Thanks for the fix!

> Fixes: c4058f96c6a5 ("netlink_delinearize: Fix suspicious calloc() call")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Acked-by: Phil Sutter <phil@nwl.cc>

Cheers, Phil