From 2b9d031235835317e41a3d6b5259f6e80390e34a Mon Sep 17 00:00:00 2001 From: Sargun Dhillon Date: Sat, 28 Dec 2019 22:24:50 -0800 Subject: [PATCH] seccomp: Check that seccomp_notif is zeroed out by the user This patch is a small change in enforcement of the uapi for SECCOMP_IOCTL_NOTIF_RECV ioctl. Specifically, the datastructure which is passed (seccomp_notif) must be zeroed out. Previously any of its members could be set to nonsense values, and we would ignore it. This ensures all fields are set to their zero value. Signed-off-by: Sargun Dhillon Reviewed-by: Christian Brauner Reviewed-by: Aleksa Sarai Acked-by: Tycho Andersen Link: https://lore.kernel.org/r/20191229062451.9467-2-sargun@sargun.me Fixes: 6a02b13b4538 ("seccomp: add a return code to trap to userspace") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook --- kernel/seccomp.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 12d2227e57867..b6ea3dcb57bfe 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1026,6 +1026,13 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, struct seccomp_notif unotif; ssize_t ret; + /* Verify that we're not given garbage to keep struct extensible. */ + ret = check_zeroed_user(buf, sizeof(unotif)); + if (ret < 0) + return ret; + if (!ret) + return -EINVAL; + memset(&unotif, 0, sizeof(unotif)); ret = down_interruptible(&filter->notif->request); -- 2.39.5