Re: [Linux-kernel-mentees] [PATCH net] xdp: Prevent kernel-infoleak in xsk_getsockopt()

On Mon, Jul 27, 2020 at 10:07:20PM -0700, Song Liu wrote:

On Mon, Jul 27, 2020 at 7:30 PM Peilin Ye [off-list ref] wrote:

quoted

xsk_getsockopt() is copying uninitialized stack memory to userspace when
`extra_stats` is `false`. Fix it by initializing `stats` with memset().

Cc: stable@vger.kernel.org

8aa5a33578e9 is not in stable branches yet, so we don't need to Cc stable.

quoted

Fixes: 8aa5a33578e9 ("xsk: Add new statistics")
Suggested-by: Dan Carpenter <redacted>
Signed-off-by: Peilin Ye <redacted>
---
 net/xdp/xsk.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 26e3bba8c204..acf001908a0d 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c

@@ -844,6 +844,8 @@ static int xsk_getsockopt(struct socket *sock, int level, int optname,
                bool extra_stats = true;
                size_t stats_size;

+               memset(&stats, 0, sizeof(stats));
+

xsk.c doesn't include linux/string.h directly, so using memset may break
build for some config combinations. We can probably just use

struct xdp_statistics stats = {};

I see. I will send v2 soon. Thank you for reviewing the patch!

Peilin Ye
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