ipsec: fix build with GCC 12

[ upstream commit 2be3834 ]

GCC 12 raises the following warning:

In function '_mm_loadu_si128',
    inlined from 'rte_mov16' at
	../lib/eal/x86/include/rte_memcpy.h:507:9,
    inlined from 'rte_mov128' at
	../lib/eal/x86/include/rte_memcpy.h:549:2,
    inlined from 'rte_memcpy_generic' at
	../lib/eal/x86/include/rte_memcpy.h:732:4,
    inlined from 'rte_memcpy' at
	../lib/eal/x86/include/rte_memcpy.h:882:10,
    inlined from 'outb_tun_pkt_prepare' at
	../lib/ipsec/esp_outb.c:224:2:
/usr/lib/gcc/x86_64-pc-linux-gnu/12.1.1/include/emmintrin.h:703:10: error:
	array subscript '__m128i_u[15]' is partly outside array bounds of
	'const uint8_t[255]' {aka 'const unsigned char[255]'}
	[-Werror=array-bounds]
  703 |   return *__P;
      |          ^~~~
In file included from ../lib/ipsec/esp_outb.c:17:
../lib/ipsec/pad.h: In function 'outb_tun_pkt_prepare':
../lib/ipsec/pad.h:10:22: note: at offset 240 into object 'esp_pad_bytes'
	of size 255
   10 | static const uint8_t esp_pad_bytes[IPSEC_MAX_PAD_SIZE] = {
      |                      ^~~~~~~~~~~~~

This patch restrict copy to minimum size.

Bugzilla ID: 1060
Fixes: 6015e6a ("ipsec: move inbound and outbound code")

Signed-off-by: Amit Prakash Shukla <amitprakashs@marvell.com>
Acked-by: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>

lib/ipsec/esp_outb.c

@@ -220,8 +220,10 @@ outb_tun_pkt_prepare(struct rte_ipsec_sa *sa, rte_be64_t sqc,
 	/* pad length */
 	pdlen -= sizeof(*espt);
 
+	RTE_ASSERT(pdlen <= sizeof(esp_pad_bytes));
+
 	/* copy padding data */
-	rte_memcpy(pt, esp_pad_bytes, pdlen);
+	rte_memcpy(pt, esp_pad_bytes, RTE_MIN(pdlen, sizeof(esp_pad_bytes)));
 
 	/* update esp trailer */
 	espt = (struct rte_esp_tail *)(pt + pdlen);
@@ -417,8 +419,10 @@ outb_trs_pkt_prepare(struct rte_ipsec_sa *sa, rte_be64_t sqc,
 	/* pad length */
 	pdlen -= sizeof(*espt);
 
+	RTE_ASSERT(pdlen <= sizeof(esp_pad_bytes));
+
 	/* copy padding data */
-	rte_memcpy(pt, esp_pad_bytes, pdlen);
+	rte_memcpy(pt, esp_pad_bytes, RTE_MIN(pdlen, sizeof(esp_pad_bytes)));
 
 	/* update esp trailer */
 	espt = (struct rte_esp_tail *)(pt + pdlen);