Messages in this thread | | | Subject | Re: [PATCH 62/64] netlink: Avoid false-positive memcpy() warning | From | Rasmus Villemoes <> | Date | Wed, 28 Jul 2021 13:24:01 +0200 |
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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
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