On 28/07/2021 07.49, Greg Kroah-Hartman wrote:
On Tue, Jul 27, 2021 at 01:58:53PM -0700, Kees Cook wrote:
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields.
Add a flexible array member to mark the end of struct nlmsghdr, and split the memcpy() to avoid false positive memcpy() warning:
memcpy: detected field-spanning write (size 32) of single field (size 16)
Signed-off-by: Kees Cook keescook@chromium.org
include/uapi/linux/netlink.h | 1 + net/netlink/af_netlink.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h index 4c0cde075c27..ddeaa748df5e 100644 --- a/include/uapi/linux/netlink.h +++ b/include/uapi/linux/netlink.h @@ -47,6 +47,7 @@ struct nlmsghdr { __u16 nlmsg_flags; /* Additional flags */ __u32 nlmsg_seq; /* Sequence number */ __u32 nlmsg_pid; /* Sending process port ID */
- __u8 contents[];
Is this ok to change a public, userspace visable, structure?
At least it should keep using a nlmsg_ prefix for consistency and reduce risk of collision with somebody having defined an object-like contents macro. But there's no guarantees in any case, of course.
Rasmus