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Handle integer overflow in uid counter. Fixes rare crashes in cache code.

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This commit is contained in:
Simon Kelley
2014-03-16 22:56:58 +00:00
parent 0c8584eabc
commit 3f7483e816
4 changed files with 23 additions and 16 deletions
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27
src/cache.c
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@@ -24,7 +24,6 @@ static struct crec *new_chain = NULL;
static int cache_inserted = 0, cache_live_freed = 0, insert_error;
static union bigname *big_free = NULL;
static int bignames_left, hash_size;
static int uid = 1;
/* type->string mapping: this is also used by the name-hash function as a mixing table. */
static const struct {
@@ -73,6 +72,17 @@ static void cache_link(struct crec *crecp);
static void rehash(int size);
static void cache_hash(struct crec *crecp);
static unsigned int next_uid(void)
{
static unsigned int uid = 1;
/* uid == 0 used to indicate CNAME to interface name. */
if (uid == 0)
uid++;
return uid++;
}
void cache_init(void)
{
struct crec *crecp;
@@ -88,7 +98,7 @@ void cache_init(void)
{
cache_link(crecp);
crecp->flags = 0;
crecp->uid = uid++;
crecp->uid = next_uid();
}
}
@@ -192,10 +202,7 @@ static void cache_free(struct crec *crecp)
{
crecp->flags &= ~F_FORWARD;
crecp->flags &= ~F_REVERSE;
crecp->uid = uid++; /* invalidate CNAMES pointing to this. */
if (uid == -1)
uid++;
crecp->uid = next_uid(); /* invalidate CNAMES pointing to this. */
if (cache_tail)
cache_tail->next = crecp;
@@ -256,7 +263,7 @@ char *cache_get_name(struct crec *crecp)
char *cache_get_cname_target(struct crec *crecp)
{
if (crecp->addr.cname.uid != -1)
if (crecp->addr.cname.uid != 0)
return cache_get_name(crecp->addr.cname.target.cache);
return crecp->addr.cname.target.int_name->name;
@@ -289,7 +296,7 @@ struct crec *cache_enumerate(int init)
static int is_outdated_cname_pointer(struct crec *crecp)
{
if (!(crecp->flags & F_CNAME) || crecp->addr.cname.uid == -1)
if (!(crecp->flags & F_CNAME) || crecp->addr.cname.uid == 0)
return 0;
/* NB. record may be reused as DS or DNSKEY, where uid is
@@ -1034,7 +1041,7 @@ void cache_reload(void)
cache->flags = F_FORWARD | F_NAMEP | F_CNAME | F_IMMORTAL | F_CONFIG;
cache->name.namep = a->alias;
cache->addr.cname.target.int_name = intr;
cache->addr.cname.uid = -1;
cache->addr.cname.uid = 0;
cache_hash(cache);
add_hosts_cname(cache); /* handle chains */
}
@@ -1242,7 +1249,7 @@ void cache_add_dhcp_entry(char *host_name, int prot,
crec->ttd = ttd;
crec->addr.addr = *host_address;
crec->name.namep = host_name;
crec->uid = uid++;
crec->uid = next_uid();
cache_hash(crec);
add_dhcp_cname(crec, ttd);