libiptc: Eliminate garbage access

When adding a rule, valgrind prints:

Syscall param socketcall.setsockopt(optval) points to uninitialised byte(s)
   at 0x4A8165A: setsockopt (in /lib64/libc.so.6)
   by 0x4857A48: iptc_commit (libiptc.c:2676)
   by 0x10E4BB: iptables_main (iptables-standalone.c:61)
   by 0x49A3349: (below main) (in /lib64/libc.so.6)
 Address 0x4b63788 is 40 bytes inside a block of size 1,448 alloc'd
   at 0x484659F: calloc (vg_replace_malloc.c:1328)
   by 0x4857654: iptc_commit (libiptc.c:2564)
   by 0x10E4BB: iptables_main (iptables-standalone.c:61)
   by 0x49A3349: (below main) (in /lib64/libc.so.6)

This is because repl->counters is not initialized upon allocation. Since
the field is an array, make use of calloc() which implicitly does the
initialization.

Fixes: e37c0dc100c51 ("Revert the recent addition of memset()'s to TC_COMMIT. One of them is bogus and the other one needs more investigation to why valgrind is complaining.")
Signed-off-by: Phil Sutter <phil@nwl.cc>

diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c
index 97823f935d1eedb274a9cfe74837977a9cb08da3..f9b7779efdba52a4c2b1ce152dc7275cf9bd0648 100644 (file)
--- a/libiptc/libiptc.c
+++ b/libiptc/libiptc.c
@@ -2554,8 +2554,8 @@ TC_COMMIT(struct xtc_handle *handle)
                        + sizeof(STRUCT_COUNTERS) * new_number;
 
        /* These are the old counters we will get from kernel */
-       repl->counters = malloc(sizeof(STRUCT_COUNTERS)
-                               * handle->info.num_entries);
+       repl->counters = calloc(handle->info.num_entries,
+                               sizeof(STRUCT_COUNTERS));
        if (!repl->counters) {
                errno = ENOMEM;
                goto out_free_repl;