From 876e480da2f74715fc70e37723e77ca16a631e35 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 8 Feb 2023 15:25:53 -0800 Subject: [PATCH] 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: Kees Cook Tested-by: Nathan Chancellor # build Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/cma.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 1d2bff9..3081559 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -479,13 +479,20 @@ 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 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) -- 2.7.4