Re: [PATCH] sched: fix string comparison in features

Steven Rostedt
2010-09-13T21:34:37Z

On Sat, 2010-09-11 at 13:44 -0400, Mathieu Desnoyers wrote:
> Incorrect handling of the following case:
>
> INTERACTIVE
> INTERACTIVE_SOMETHING_ELSE
>
> The comparison only checks up to each element's length.

Replace all your changes with mine, and you have the same effect ;-)

-- Steve

>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> ---
> kernel/sched.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> Index: linux-2.6-lttng.git/kernel/sched.c
> ===================================================================
> --- linux-2.6-lttng.git.orig/kernel/sched.c
> +++ linux-2.6-lttng.git/kernel/sched.c
> @@ -722,7 +722,7 @@ sched_feat_write(struct file *filp, cons
> {
> char buf[64];
> char *cmp = buf;

- char *cmp = buf;
+ char *cmp;

> - int neg = 0;
> + int neg = 0, cmplen;
> int i;
>
> if (cnt > 63)
> @@ -732,15 +732,24 @@ sched_feat_write(struct file *filp, cons
> return -EFAULT;
>
> buf[cnt] = 0;
> + for (i = 0; i < cnt; i++) {
> + if (buf[i] == '\n' || buf[i] == ' ') {
> + buf[i] = 0;
> + break;
> + }
> + }

+ cmp = strstrip(buf);

>
> if (strncmp(buf, "NO_", 3) == 0) {
> neg = 1;
> cmp += 3;
> }
>
> + cmplen = strlen(cmp);
> for (i = 0; sched_feat_names[i]; i++) {
> int len = strlen(sched_feat_names[i]);

- int len = strlen(sched_feat_names[i]);

>
> + if (cmplen != len)
> + continue;
> if (strncmp(cmp, sched_feat_names[i], len) == 0) {

- if (strncmp(cmp, sched_feat_names[i], len) == 0) {
+ if (strcmp(cmp, sched_feat_names[i]) == 0) {

> if (neg)
> sysctl_sched_features &= ~(1UL << i);