netfilter: ebtables: zero chainstack array

sashiko reports:
 looking at ebtables table
 translation, could a sparse cpu_possible_mask lead to an uninitialized pointer
 free?

 If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible,
 but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at
 CPU 2, the cleanup loop will blindly decrement and call vfree() on
 newinfo->chainstack[1].

Not a real-world bug, such allocation isn't expected to fail
in the first place.

Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 5b74ff827493fad4533b1b66caddbe5f35de355f..48187598cdd03a2c33b794337869e1f6df003d54 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -921,8 +921,7 @@ static int translate_table(struct net *net, const char *name,
                 * if an error occurs
                 */
                newinfo->chainstack =
-                       vmalloc_array(nr_cpu_ids,
-                                     sizeof(*(newinfo->chainstack)));
+                       vcalloc(nr_cpu_ids, sizeof(*(newinfo->chainstack)));
                if (!newinfo->chainstack)
                        return -ENOMEM;
                for_each_possible_cpu(i) {