lib/vsprintf.c: Avoid possible unaligned accesses in %pI6c

Jens Rosenboom noticed that a possibly unaligned const char*
is cast to a const struct in6_addr *.

Avoid this at the cost of a struct in6_addr copy on the stack.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 10 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index cb8a112030bb..a1941f8d205f 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -671,7 +671,7 @@ static char *ip4_string(char *p, const u8 *addr, bool leading_zeros)
         return p;
 }
 
-static char *ip6_compressed_string(char *p, const struct in6_addr *addr)
+static char *ip6_compressed_string(char *p, const char *addr)
 {
         int i;
         int j;
@@ -683,7 +683,12 @@ static char *ip6_compressed_string(char *p, const struct in6_addr *addr)
         u8 hi;
         u8 lo;
         bool needcolon = false;
-        bool useIPv4 = ipv6_addr_v4mapped(addr) || ipv6_addr_is_isatap(addr);
+        bool useIPv4;
+        struct in6_addr in6;
+
+        memcpy(&in6, addr, sizeof(struct in6_addr));
+
+        useIPv4 = ipv6_addr_v4mapped(&in6) || ipv6_addr_is_isatap(&in6);
 
         memset(zerolength, 0, sizeof(zerolength));
 
@@ -695,7 +700,7 @@ static char *ip6_compressed_string(char *p, const struct in6_addr *addr)
         /* find position of longest 0 run */
         for (i = 0; i < range; i++) {
                 for (j = i; j < range; j++) {
-                        if (addr->s6_addr16[j] != 0)
+                        if (in6.s6_addr16[j] != 0)
                                 break;
                         zerolength[i]++;
                 }
@@ -722,7 +727,7 @@ static char *ip6_compressed_string(char *p, const struct in6_addr *addr)
                         needcolon = false;
                 }
                 /* hex u16 without leading 0s */
-                word = ntohs(addr->s6_addr16[i]);
+                word = ntohs(in6.s6_addr16[i]);
                 hi = word >> 8;
                 lo = word & 0xff;
                 if (hi) {
@@ -741,19 +746,19 @@ static char *ip6_compressed_string(char *p, const struct in6_addr *addr)
         if (useIPv4) {
                 if (needcolon)
                         *p++ = ':';
-                p = ip4_string(p, &addr->s6_addr[12], false);
+                p = ip4_string(p, &in6.s6_addr[12], false);
         }
 
         *p = '\0';
         return p;
 }
 
-static char *ip6_string(char *p, const struct in6_addr *addr, const char *fmt)
+static char *ip6_string(char *p, const char *addr, const char *fmt)
 {
         int i;
         for (i = 0; i < 8; i++) {
-                p = pack_hex_byte(p, addr->s6_addr[2 * i]);
-                p = pack_hex_byte(p, addr->s6_addr[2 * i + 1]);
+                p = pack_hex_byte(p, *addr++);
+                p = pack_hex_byte(p, *addr++);
                 if (fmt[0] == 'I' && i != 7)
                         *p++ = ':';
         }
@@ -768,9 +773,9 @@ static char *ip6_addr_string(char *buf, char *end, const u8 *addr,
         char ip6_addr[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255")];
 
         if (fmt[0] == 'I' && fmt[2] == 'c')
-                ip6_compressed_string(ip6_addr, (const struct in6_addr *)addr);
+                ip6_compressed_string(ip6_addr, addr);
         else
-                ip6_string(ip6_addr, (const struct in6_addr *)addr, fmt);
+                ip6_string(ip6_addr, addr, fmt);
 
         return string(buf, end, ip6_addr, spec);
 }