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iptables/SOURCES/0065-libxtables-Fix-for-war...

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From f6915482a365373c5892752f87086740b84fe2d3 Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Tue, 15 Mar 2022 12:17:25 +0100
Subject: [PATCH] libxtables: Fix for warning in xtables_ipmask_to_numeric
Gcc complains:
| xtables.c: In function 'xtables_ipmask_to_numeric':
| xtables.c:1491:34: warning: '__builtin___sprintf_chk' may write a terminating nul past the end of the destination [-Wformat-overflow=]
| 1491 | sprintf(buf, "/%s", xtables_ipaddr_to_numeric(mask));
| | ^
Indeed, xtables_ipaddr_to_numeric() returns a pointer to a 20 byte
buffer and xtables_ipmask_to_numeric() writes its content into a buffer
of same size at offset 1. Yet length of returned string is deterministic
as it is an IPv4 address. So shrink it to the minimum of 16 bytes which
eliminates the warning as well.
Fixes: a96166c24eaac ("libxtables: add xtables_ip[6]mask_to_cidr")
Signed-off-by: Phil Sutter <phil@nwl.cc>
(cherry picked from commit 0c8e253595bd80e4ddd73230d079e33cd5420b32)
---
libxtables/xtables.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libxtables/xtables.c b/libxtables/xtables.c
index cb380ad61ccb5..2e6c68292f16a 100644
--- a/libxtables/xtables.c
+++ b/libxtables/xtables.c
@@ -1389,7 +1389,7 @@ void xtables_param_act(unsigned int status, const char *p1, ...)
const char *xtables_ipaddr_to_numeric(const struct in_addr *addrp)
{
- static char buf[20];
+ static char buf[16];
const unsigned char *bytep = (const void *)&addrp->s_addr;
sprintf(buf, "%u.%u.%u.%u", bytep[0], bytep[1], bytep[2], bytep[3]);
--
2.40.0