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Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: use strscpy() to avoid buffer
 overrun
To:     Tim Gardner <tim.gardner@canonical.com>,
        intel-gfx@lists.freedesktop.org
Cc:     Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <dc88e195-949c-bb46-b7d3-18e90df9b064@canonical.com>
 <20210916122649.12691-1-tim.gardner@canonical.com>
From:   Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Organization: Intel Corporation UK Plc
Message-ID: <77c6c991-b7b4-0362-63ca-17a801187f7a@linux.intel.com>
Date:   Fri, 17 Sep 2021 08:37:21 +0100
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On 16/09/2021 13:26, Tim Gardner wrote:
> In capture_vma() Coverity complains of a possible buffer overrun. Even
> though this is a static function where all call sites can be checked,
> limiting the copy length could save some future grief.
> 
> CID 93300 (#1 of 1): Copy into fixed size buffer (STRING_OVERFLOW)
> 4. fixed_size_dest: You might overrun the 16-character fixed-size string c->name
>     by copying name without checking the length.
> 5. parameter_as_source: Note: This defect has an elevated risk because the
>     source argument is a parameter of the current function.
> 1326        strcpy(c->name, name);
> 
> Fix any possible overflows by using strscpy() which guarantees NULL termination.
> 
> Also correct 2 other strcpy() call sites with the same potential for Coverity
> warnings or overruns.
> 
> v2 - Change $SUBJECT from "drm/i915: zero fill vma name buffer"
>       Use strscpy() instead of strncpy(). Its a much simpler change.
> 
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: intel-gfx@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
> ---
>   drivers/gpu/drm/i915/i915_gpu_error.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index 9cf6ac575de1..7f246f51959d 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -1015,7 +1015,7 @@ i915_vma_coredump_create(const struct intel_gt *gt,
>   		return NULL;
>   	}
>   
> -	strcpy(dst->name, name);
> +	strscpy(dst->name, name, sizeof(dst->name));
>   	dst->next = NULL;
>   
>   	dst->gtt_offset = vma->node.start;
> @@ -1279,7 +1279,7 @@ static bool record_context(struct i915_gem_context_coredump *e,
>   	rcu_read_lock();
>   	task = pid_task(ctx->pid, PIDTYPE_PID);
>   	if (task) {
> -		strcpy(e->comm, task->comm);
> +		strscpy(e->comm, task->comm, sizeof(e->comm));
>   		e->pid = task->pid;
>   	}
>   	rcu_read_unlock();
> @@ -1323,7 +1323,7 @@ capture_vma(struct intel_engine_capture_vma *next,
>   		return next;
>   	}
>   
> -	strcpy(c->name, name);
> +	strscpy(c->name, name, sizeof(c->name));
>   	c->vma = vma; /* reference held while active */
>   
>   	c->next = next;
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko