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[v2,47/63] intel_th: msu: Use memset_startat() for clearing hw header

Message ID 20210818060533.3569517-48-keescook@chromium.org (mailing list archive)
State Not Applicable
Delegated to: Johannes Berg
Headers show
Series Introduce strict memcpy() bounds checking | expand

Commit Message

Kees Cook Aug. 18, 2021, 6:05 a.m. UTC
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Use memset_startat() so memset() doesn't get confused about writing
beyond the destination member that is intended to be the starting point
of zeroing through the end of the struct.

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/hwtracing/intel_th/msu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Comments

Alexander Shishkin Aug. 24, 2021, 7:38 a.m. UTC | #1
Kees Cook <keescook@chromium.org> writes:

> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
>
> Use memset_startat() so memset() doesn't get confused about writing
> beyond the destination member that is intended to be the starting point
> of zeroing through the end of the struct.
>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

> ---
>  drivers/hwtracing/intel_th/msu.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
> index 432ade0842f6..70a07b4e9967 100644
> --- a/drivers/hwtracing/intel_th/msu.c
> +++ b/drivers/hwtracing/intel_th/msu.c
> @@ -658,13 +658,11 @@ static void msc_buffer_clear_hw_header(struct msc *msc)
>  
>  	list_for_each_entry(win, &msc->win_list, entry) {
>  		unsigned int blk;
> -		size_t hw_sz = sizeof(struct msc_block_desc) -
> -			offsetof(struct msc_block_desc, hw_tag);
>  
>  		for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
>  			struct msc_block_desc *bdesc = sg_virt(sg);
>  
> -			memset(&bdesc->hw_tag, 0, hw_sz);
> +			memset_startat(bdesc, 0, hw_tag);
>  		}
>  	}
>  }
> -- 
> 2.30.2
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Patch

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index 432ade0842f6..70a07b4e9967 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -658,13 +658,11 @@  static void msc_buffer_clear_hw_header(struct msc *msc)
 
 	list_for_each_entry(win, &msc->win_list, entry) {
 		unsigned int blk;
-		size_t hw_sz = sizeof(struct msc_block_desc) -
-			offsetof(struct msc_block_desc, hw_tag);
 
 		for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
 			struct msc_block_desc *bdesc = sg_virt(sg);
 
-			memset(&bdesc->hw_tag, 0, hw_sz);
+			memset_startat(bdesc, 0, hw_tag);
 		}
 	}
 }