On Sunday 2011-07-10 21:53, Jan Engelhardt wrote:
>On Sunday 2011-07-10 20:23, Bart De Schuymer wrote:
>
>> Hi all,
>>
>> I just released a new version of the ebtables tool.
I had produced this patch in response to a gcc warning. Compiles, but
not tested.
--->8---
From: Jan Engelhardt <jengelh@xxxxxxxxxx>
Date: 2011-07-11 01:11 +0200
libebt_among: fix undefined behavior on dereference of typepunned ptr
extensions/ebt_among.c: In function ‘create_wormhash’:
extensions/ebt_among.c:250:4: warning: dereferencing type-punned pointer will break strict-aliasing rules
extensions/ebt_among.c:261:3: warning: dereferencing type-punned pointer will break strict-aliasing rules
---
extensions/ebt_among.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
Index: ebtables-v2.0.10-1/extensions/ebt_among.c
===================================================================
--- ebtables-v2.0.10-1.orig/extensions/ebt_among.c
+++ ebtables-v2.0.10-1/extensions/ebt_among.c
@@ -183,7 +183,7 @@ static struct ebt_mac_wormhash *create_w
char *endptr;
struct ebt_mac_wormhash *workcopy, *result, *h;
unsigned char mac[6];
- unsigned char ip[4];
+ uint32_t ip;
int nmacs = 0;
int i;
char token[4];
@@ -222,16 +222,18 @@ static struct ebt_mac_wormhash *create_w
ebt_print_error("MAC parse error: %.20s", anchor);
return NULL;
}
+ ip = 0;
if (*pc == '=') {
/* an IP follows the MAC; collect similarly to MAC */
pc++;
anchor = pc;
- for (i = 0; i < 3; i++) {
+ for (i = 3; i > 0; --i) {
if (read_until(&pc, ".", token, 3) < 0 || token[0] == 0) {
ebt_print_error("IP parse error: %.20s", anchor);
return NULL;
}
- ip[i] = strtol(token, &endptr, 10);
+ /* 0xFF warrants using 8 - not CHAR_BIT. */
+ ip |= (strtoul(token, &endptr, 10) & 0xFF) << (8 * i);
if (*endptr) {
ebt_print_error("IP parse error: %.20s", anchor);
return NULL;
@@ -242,23 +244,21 @@ static struct ebt_mac_wormhash *create_w
ebt_print_error("IP parse error: %.20s", anchor);
return NULL;
}
- ip[3] = strtol(token, &endptr, 10);
+ ip |= strtoul(token, &endptr, 10) & 0xFF;
if (*endptr) {
ebt_print_error("IP parse error: %.20s", anchor);
return NULL;
}
- if (*(uint32_t*)ip == 0) {
+ ip = htonl(ip);
+ if (ip == 0) {
ebt_print_error("Illegal IP 0.0.0.0");
return NULL;
}
- } else {
- /* no IP, we set it to 0.0.0.0 */
- memset(ip, 0, 4);
}
/* we have collected MAC and IP, so we add an entry */
memcpy(((char *) workcopy->pool[nmacs].cmp) + 2, mac, 6);
- workcopy->pool[nmacs].ip = *(const uint32_t *) ip;
+ workcopy->pool[nmacs].ip = ip;
nmacs++;
/* re-allocate memory if needed */
--
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