[PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Justin Stitt]

When building with Clang we encounter these warnings:
| net/netfilter/xt_TPROXY.c:173:5: error: format specifies type 'unsigned
| char' but the argument has type 'int' [-Werror,-Wformat] tproto,
| &iph->saddr, ntohs(hp->source),
-
| net/netfilter/xt_TPROXY.c:181:4: error: format specifies type 'unsigned
| char' but the argument has type 'int' [-Werror,-Wformat] tproto,
| &iph->saddr, ntohs(hp->source),

The format specifier `%hhu` refers to a u8 while tproto is an int. In
this case we weren't losing any data because ipv6_find_hdr returns an
int but its return value (nexthdr) is a u8. This u8 gets widened to an
int when returned from ipv6_find_hdr and assigned to tproto. The
previous format specifier is functionally fine but still produces a
warning due to a type mismatch.

The fix is simply to listen to Clang and change `%hhu` to `%d` for both
instances of the warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
It should be noted that for this entire file to build without -Wformat
warnings you should apply this `ntohs` patch which fixed many, many
-Wformat warnings in the kernel.
https://lore.kernel.org/all/20220608223539.470472-1-justinstitt@xxxxxxxxxx/

 net/netfilter/xt_TPROXY.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 459d0696c91a..5d74abffc94f 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
 
-		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
+		pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
 			 tproto, &iph->saddr, ntohs(hp->source),
 			 laddr, ntohs(lport), skb->mark);
 
@@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
+	pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
 		 tproto, &iph->saddr, ntohs(hp->source),
 		 &iph->daddr, ntohs(hp->dest), skb->mark);
 
-- 
2.37.0.rc0.161.g10f37bed90-goog