pktgen: use dynamic allocation for debug print buffer

After the removal of the VLA, we get a harmless warning about a large
stack frame:

net/core/pktgen.c: In function 'pktgen_if_write':
net/core/pktgen.c:1710:1: error: the frame size of 1076 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

The function was previously shown to be safe despite hitting
the 1024 bye warning level. To get rid of the annoyging warning,
while keeping it readable, this changes it to use strndup_user().

Obviously this is not a fast path, so the kmalloc() overhead
can be disregarded.

Fixes: 35951393bbff ("pktgen: Remove VLA usage")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index e2d6ae3b290b9a0fdcdf1f22ae74500e54b3d765..fd65761e1fed2511c2460a256f4126dbbeb9acd5 100644 (file)
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -906,13 +906,14 @@ static ssize_t pktgen_if_write(struct file *file,
        i += len;
 
        if (debug) {
-               size_t copy = min_t(size_t, count, 1023);
-               char tb[1024];
-               if (copy_from_user(tb, user_buffer, copy))
-                       return -EFAULT;
-               tb[copy] = 0;
-               pr_debug("%s,%lu  buffer -:%s:-\n",
-                        name, (unsigned long)count, tb);
+               size_t copy = min_t(size_t, count + 1, 1024);
+               char *tp = strndup_user(user_buffer, copy);
+
+               if (IS_ERR(tp))
+                       return PTR_ERR(tp);
+
+               pr_debug("%s,%zu  buffer -:%s:-\n", name, count, tp);
+               kfree(buf);
        }
 
        if (!strcmp(name, "min_pkt_size")) {