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

Kees Cook
2021-08-18T06:12:52Z

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(-)

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