Subrata Modak wrote:
> On Fri, Oct 17, 2008 at 7:58 PM, Daniel Gollub <[EMAIL PROTECTED]> wrote:
>
>> Hi,
>>
>> with GCC 4.3 and with LTP CVS snapshot from today i got following warning
>> when
>> using the GCC Object Checking Builtins:
>>
>>
>> cc -O2 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -g
>> -Wall -O2 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -g
>> -I../../../../include -Wall pec_listener.c -L../../../../lib -lltp -o
>> pec_listener
>> In function 'memset',
>> inlined from 'netlink_recv' at pec_listener.c:112,
>> inlined from 'main' at pec_listener.c:270:
>> /usr/include/bits/string3.h:85: warning: call to
>> __builtin___memset_chk will always overflow destination buffer
>
>
> Li,
>
> Your comment on this ?
>
It's not a correct fix, the patch initializes the message header only.
Below is a correct one:
Allocate a buffer large enough to hold NLMSG_SPACE(MAX_MSG_SIZE).
Signed-off-by: Li Zefan <[EMAIL PROTECTED]>
---
pec_listener.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)
--- a/testcases/kernel/connectors/pec/pec_listener.c 2008-10-20
09:57:39.000000000 +0800
+++ b/testcases/kernel/connectors/pec/pec_listener.c 2008-10-20
10:09:23.000000000 +0800
@@ -44,6 +44,8 @@ static __u32 seq;
static int exit_flag;
static struct sigaction sigint_action;
+struct nlmsghdr *nlhdr;
+
/*
* Handler for signal int. Set exit flag.
*
@@ -64,14 +66,10 @@ static void sigint_handler(int __attribu
static int netlink_send(int sd, struct sockaddr_nl *to, struct cn_msg *cnmsg)
{
int ret;
- char buf[MAX_MSG_SIZE];
- struct nlmsghdr *nlhdr;
struct iovec iov;
struct msghdr msg;
- memset(buf, 0, MAX_MSG_SIZE);
-
- nlhdr = (struct nlmsghdr *)buf;
+ memset(nlhdr, 0, NLMSG_SPACE(MAX_MSG_SIZE));
nlhdr->nlmsg_seq = seq++;
nlhdr->nlmsg_pid = getpid();
@@ -100,12 +98,10 @@ static int netlink_send(int sd, struct s
*
* @sd: socket descripor
* @from: source sockaddr
- * @buf: buffer for storing the package
*/
-static int netlink_recv(int sd, struct sockaddr_nl *from, char *buf)
+static int netlink_recv(int sd, struct sockaddr_nl *from)
{
int ret;
- struct nlmsghdr *nlhdr = (struct nlmsghdr *)buf;
struct iovec iov;
struct msghdr msg;
@@ -214,14 +210,18 @@ int main(int argc, char **argv)
int sd;
struct sockaddr_nl l_local;
struct sockaddr_nl src_addr;
- char buf[MAX_MSG_SIZE];
struct pollfd pfd;
sigint_action.sa_flags = SA_ONESHOT;
sigint_action.sa_handler = &sigint_handler;
sigaction(SIGINT, &sigint_action, NULL);
- /* Create and bind socket */
+ nlhdr = malloc(NLMSG_SPACE(MAX_MSG_SIZE));
+ if (!nlhdr) {
+ fprintf(stderr, "lack of memory\n");
+ exit(1);
+ }
+
sd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
if (sd == -1) {
fprintf(stderr, "failed to create socket\n");
@@ -257,7 +257,6 @@ int main(int argc, char **argv)
pfd.events = POLLIN;
pfd.revents = 0;
while (!exit_flag) {
- struct nlmsghdr *nlhdr;
ret = poll(&pfd, 1, -1);
if (ret == 0 || (ret == -1 && errno != EINTR)) {
@@ -267,7 +266,7 @@ int main(int argc, char **argv)
} else if (ret == -1 && errno == EINTR)
break;
- ret = netlink_recv(sd, &src_addr, buf);
+ ret = netlink_recv(sd, &src_addr);
if (ret == 0)
break;
@@ -278,8 +277,6 @@ int main(int argc, char **argv)
fprintf(stderr, "failed to receive from netlink\n");
exit(1);
} else {
- nlhdr = (struct nlmsghdr *)buf;
-
switch (nlhdr->nlmsg_type) {
case NLMSG_ERROR:
fprintf(stderr, "err message recieved.\n");
@@ -304,6 +301,7 @@ int main(int argc, char **argv)
}
close(sd);
+ free(nlhdr);
while (fsync(STDOUT_FILENO) == -1) {
if (errno != EIO)
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