Commit 876e480d authored by Kees Cook's avatar Kees Cook Committed by Jason Gunthorpe
Browse files

RDMA/cma: Distinguish between sockaddr_in and sockaddr_in6 by size 

Clang can do some aggressive inlining, which provides it with greater
visibility into the sizes of various objects that are passed into
helpers. Specifically, compare_netdev_and_ip() can see through the type
given to the "sa" argument, which means it can generate code for "struct
sockaddr_in" that would have been passed to ipv6_addr_cmp() (that expects
to operate on the larger "struct sockaddr_in6"), which would result in a
compile-time buffer overflow condition detected by memcmp(). Logically,
this state isn't reachable due to the sa_family assignment two callers
above and the check in compare_netdev_and_ip(). Instead, provide a
compile-time check on sizes so the size-mismatched code will be elided
when inlining. Avoids the following warning from Clang:

../include/linux/fortify-string.h:652:4: error: call to '__read_overflow' declared with 'error' attribute: detected read beyond size of object (1st parameter)
                        __read_overflow();
                        ^
note: In function 'cma_netevent_callback'
note:   which inlined function 'node_from_ndev_ip'
1 error generated.

When the underlying object size is not known (e.g. with GCC and older
Clang), the result of __builtin_object_size() is SIZE_MAX, which will also
compile away, leaving the code as it was originally.

Link: https://lore.kernel.org/r/20230208232549.never.139-kees@kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1687


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 5ff31dfc

drivers/infiniband/core/cma.c

+12 −5
Original line number Diff line number Diff line
@@ -479,15 +479,22 @@ static int compare_netdev_and_ip(int ifindex_a, struct sockaddr *sa, 
	if (sa->sa_family != sb->sa_family)

		return sa->sa_family - sb->sa_family;



	if (sa->sa_family == AF_INET)

		return memcmp((char *)&((struct sockaddr_in *)sa)->sin_addr,

			      (char *)&((struct sockaddr_in *)sb)->sin_addr,

	if (sa->sa_family == AF_INET &&

	    __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in)) {

		return memcmp(&((struct sockaddr_in *)sa)->sin_addr,

			      &((struct sockaddr_in *)sb)->sin_addr,

			      sizeof(((struct sockaddr_in *)sa)->sin_addr));

	}



	if (sa->sa_family == AF_INET6 &&

	    __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in6)) {

		return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,

				     &((struct sockaddr_in6 *)sb)->sin6_addr);

	}



	return -1;

}



static int cma_add_id_to_tree(struct rdma_id_private *node_id_priv)

{

	struct rb_node **new, *parent = NULL;