Document some coverity false positives.

diff --git a/ipv6.c b/ipv6.c
index 3bd52068ede3d60eddcd324475d2e5a8a7a84980..d1e2d05f4e3aa3fcb260ddbfa0e428c7534cfd4e 100644 (file)
--- a/ipv6.c
+++ b/ipv6.c
@@ -409,21 +409,25 @@ ipv6_makeaddr(struct in6_addr *addr, struct interface *ifp,
 int
 ipv6_makeprefix(struct in6_addr *prefix, const struct in6_addr *addr, int len)
 {
-       int bytelen, bitlen;
+       int bytes, bits;
 
        if (len < 0 || len > 128) {
                errno = EINVAL;
                return -1;
        }
 
-       bytelen = len / NBBY;
-       bitlen = len % NBBY;
-       memcpy(&prefix->s6_addr, &addr->s6_addr, (size_t)bytelen);
-       if (bitlen != 0)
-               prefix->s6_addr[bytelen] =
-                   (uint8_t)(prefix->s6_addr[bytelen] >> (NBBY - bitlen));
-       memset((char *)prefix->s6_addr + bytelen, 0,
-           sizeof(prefix->s6_addr) - (size_t)bytelen);
+       bytes = len / NBBY;
+       bits = len % NBBY;
+       memcpy(&prefix->s6_addr, &addr->s6_addr, (size_t)bytes);
+       if (bits != 0) {
+               /* Coverify false positive.
+                * bytelen cannot be 16 if bitlen is non zero */
+               /* coverity[overrun-local] */
+               prefix->s6_addr[bytes] =
+                   (uint8_t)(prefix->s6_addr[bytes] >> (NBBY - bits));
+       }
+       memset((char *)prefix->s6_addr + bytes, 0,
+           sizeof(prefix->s6_addr) - (size_t)bytes);
        return 0;
 }
 
@@ -444,8 +448,12 @@ ipv6_mask(struct in6_addr *mask, int len)
        bits = len % NBBY;
        for (i = 0; i < bytes; i++)
                mask->s6_addr[i] = 0xff;
-       if (bits)
+       if (bits) {
+               /* Coverify false positive.
+                * bytelen cannot be 16 if bitlen is non zero */
+               /* coverity[overrun-local] */
                mask->s6_addr[bytes] = masks[bits - 1];
+       }
        return 0;
 }
 
@@ -2350,7 +2358,8 @@ ipv6_buildroutes(struct dhcpcd_ctx *ctx)
        }
 
        /* Free any routes we failed to add/change */
-       while ((rt = TAILQ_FIRST(&dnr))) {
+       /* coverity[use_after_free] */
+       while ((rt = TAILQ_FIRST(&dnr)) != NULL) {
                TAILQ_REMOVE(&dnr, rt, next);
                free(rt);
        }
@@ -2358,7 +2367,7 @@ ipv6_buildroutes(struct dhcpcd_ctx *ctx)
        /* Remove old routes we used to manage
         * If we own the default route, but not RA management itself
         * then we need to preserve the last best default route we had */
-       while ((rt = TAILQ_LAST(ctx->ipv6->routes, rt6_head))) {
+       while ((rt = TAILQ_LAST(ctx->ipv6->routes, rt6_head)) != NULL) {
                TAILQ_REMOVE(ctx->ipv6->routes, rt, next);
                if (find_route6(nrs, rt) == NULL) {
                        o = rt->iface->options->options;