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net: tap: replace snprintf with g_strdup_printf calls

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When invoking qemu-bridge-helper in 'net_bridge_run_helper',
instead of using fixed sized buffers, use dynamically allocated
ones initialised and returned by g_strdup_printf().

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Prasad J Pandit 2019-07-23 16:17:54 +05:30 committed by Jason Wang
parent 3283dde4b5
commit 389abe1dd1
1 changed files with 11 additions and 8 deletions
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19
net/tap.c
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@ -498,9 +498,9 @@ static int net_bridge_run_helper(const char *helper, const char *bridge,
}
if (pid == 0) {
int open_max = sysconf(_SC_OPEN_MAX), i;
char fd_buf[6+10];
char br_buf[6+IFNAMSIZ] = {0};
char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 15];
char *fd_buf = NULL;
char *br_buf = NULL;
char *helper_cmd = NULL;
for (i = 3; i < open_max; i++) {
if (i != sv[1]) {
@ -508,17 +508,17 @@ static int net_bridge_run_helper(const char *helper, const char *bridge,
}
}
snprintf(fd_buf, sizeof(fd_buf), "%s%d", "--fd=", sv[1]);
fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]);
if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
/* assume helper is a command */
if (strstr(helper, "--br=") == NULL) {
snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
br_buf = g_strdup_printf("%s%s", "--br=", bridge);
}
snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s",
helper, "--use-vnet", fd_buf, br_buf);
helper_cmd = g_strdup_printf("%s %s %s %s", helper,
"--use-vnet", fd_buf, br_buf ? br_buf : "");
parg = args;
*parg++ = (char *)"sh";
@ -527,10 +527,11 @@ static int net_bridge_run_helper(const char *helper, const char *bridge,
*parg++ = NULL;
execv("/bin/sh", args);
g_free(helper_cmd);
} else {
/* assume helper is just the executable path name */
snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
br_buf = g_strdup_printf("%s%s", "--br=", bridge);
parg = args;
*parg++ = (char *)helper;
@ -541,6 +542,8 @@ static int net_bridge_run_helper(const char *helper, const char *bridge,
execv(helper, args);
}
g_free(fd_buf);
g_free(br_buf);
_exit(1);
} else {