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ss: Fix allocation of cong control alg name

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On Fri, 2015-05-29 at 13:30 +0300, Vadim Kochan wrote:
> From: Vadim Kochan <vadim4j@gmail.com>
>
> Use strdup instead of malloc, and get rid of bad strcpy.
>
> Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
> ---
>  misc/ss.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/misc/ss.c b/misc/ss.c
> index 347e3a1..a719466 100644
> --- a/misc/ss.c
> +++ b/misc/ss.c
> @@ -1908,8 +1908,7 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r,
>
>  		if (tb[INET_DIAG_CONG]) {
>  			const char *cong_attr = rta_getattr_str(tb[INET_DIAG_CONG]);
> -			s.cong_alg = malloc(strlen(cong_attr + 1));
> -			strcpy(s.cong_alg, cong_attr);
> +			s.cong_alg = strdup(cong_attr);
>  		}
>
>  		if (TCPI_HAS_OPT(info, TCPI_OPT_WSCALE)) {

I doubt TCP_CA_NAME_MAX will ever change in the kernel : 16 bytes.

Its typically "cubic" and less than 8 bytes.

Using 8 bytes to point to a malloc(8) is a waste.

Please remove the memory allocation, or store the pointer, since
tcp_show_info() does the malloc()/free() before return.
This commit is contained in:
Eric Dumazet 2015-05-29 04:04:05 -07:00 committed by Stephen Hemminger
parent b6907403ef
commit d2055ea597
1 changed files with 6 additions and 9 deletions
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15
misc/ss.c
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@ -755,7 +755,7 @@ struct tcpstat
int timer;
int timeout;
int probes;
char *cong_alg;
char cong_alg[16];
double rto, ato, rtt, rttvar;
int qack, cwnd, ssthresh, backoff;
double send_bps;
@ -1664,7 +1664,7 @@ static void tcp_stats_print(struct tcpstat *s)
printf(" ecnseen");
if (s->has_fastopen_opt)
printf(" fastopen");
if (s->cong_alg)
if (s->cong_alg[0])
printf(" %s", s->cong_alg);
if (s->has_wscale_opt)
printf(" wscale:%d,%d", s->snd_wscale, s->rcv_wscale);
@ -1906,11 +1906,10 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r,
s.has_fastopen_opt = TCPI_HAS_OPT(info, TCPI_OPT_SYN_DATA);
}
if (tb[INET_DIAG_CONG]) {
const char *cong_attr = rta_getattr_str(tb[INET_DIAG_CONG]);
s.cong_alg = malloc(strlen(cong_attr + 1));
strcpy(s.cong_alg, cong_attr);
}
if (tb[INET_DIAG_CONG])
strncpy(s.cong_alg,
rta_getattr_str(tb[INET_DIAG_CONG]),
sizeof(s.cong_alg) - 1);
if (TCPI_HAS_OPT(info, TCPI_OPT_WSCALE)) {
s.has_wscale_opt = true;
@ -1984,8 +1983,6 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r,
tcp_stats_print(&s);
if (s.dctcp)
free(s.dctcp);
if (s.cong_alg)
free(s.cong_alg);
}
}