linux-kernel - Re: [PATCH 1/3] perf: Return proper values for user stack errors

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Message-ID: <20180416165430.GB3202@kernel.org>
Date:   Mon, 16 Apr 2018 13:54:30 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andi Kleen <andi@...stfloor.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        hpa@...or.com, Namhyung Kim <namhyung@...nel.org>,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de, x86@...nel.org
Subject: Re: [PATCH 1/3] perf: Return proper values for user stack errors

Em Sun, Apr 15, 2018 at 11:23:50AM +0200, Jiri Olsa escreveu:
> Return immediately when we find issue in the user
> stack checks. The error value could get overwritten
> by following check for PERF_SAMPLE_REGS_INTR.
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

Also, since you're sending this to syskaller-bugs, was this something
reported by that tool? If so I think we should communicate with him,
like described in its docs, no? /me goes to find the doc snippet...



>  kernel/events/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index fc1c330c6bd6..4d997bc064d2 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -10191,9 +10191,9 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
>  		 * __u16 sample size limit.
>  		 */
>  		if (attr->sample_stack_user >= USHRT_MAX)
> -			ret = -EINVAL;
> +			return -EINVAL;
>  		else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
> -			ret = -EINVAL;
> +			return -EINVAL;
>  	}
>  
>  	if (!attr->sample_max_stack)
> -- 
> 2.13.6