We test whenever the path of unix-domain socket address is non-empty and strictly-less than the length of the path buffer. Both these conditions are wrong: the socket can be unnamed, with empty path, or socket can have pathname null-terminated _after_ the sun_path buffer, since we provided more room when asking kernel.
So on one side, allow empty, unnamed sockets (and adjust the test for abstract socket too - only do that if the socket is not unnamed), and on another side, allow path length to be up to our own maximum, - we have up to size of sockaddr_storage there. While at it, fix the duplication of regular pathname socket to not require trailing \0 (since it can be missing for unnamed sockets). Fixes: 4cfd970ec188558daa6214f26203fe553fb1e01f (first in 6.1.0) Fixes: http://bugs.debian.org/993145 Signed-off-by: Michael Tokarev <m...@tls.msk.ru> Cc: qemu-sta...@nongnu.org -- Two questions. 1. Why do we store the name of the socket to start with? 2. The code in the abstract socket case should not use g_strndup but g_memdup instead, since the whole thing is a blob of the given length, not a \0-terminated string. --- util/qemu-sockets.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c index f2f3676d1f..7c83d81792 100644 --- a/util/qemu-sockets.c +++ b/util/qemu-sockets.c @@ -1345,13 +1345,20 @@ socket_sockaddr_to_address_unix(struct sockaddr_storage *sa, SocketAddress *addr; struct sockaddr_un *su = (struct sockaddr_un *)sa; - assert(salen >= sizeof(su->sun_family) + 1 && - salen <= sizeof(struct sockaddr_un)); + /* there's a corner case when trailing \0 does not fit into + * sockaddr_un. Compare length with sizeof(sockaddr_storage), + * not with sizeof(sockaddr_un), since this is what we actually + * provide, to ensure we had no truncation and a room for + * the trailing \0 which we add below. + * When salen == sizeof(sun_family) it is unnamed socket, + * and when first byte of sun_path is \0, it is abstract. */ + assert(salen >= sizeof(su->sun_family) && + salen <= sizeof(struct sockaddr_storage)); addr = g_new0(SocketAddress, 1); addr->type = SOCKET_ADDRESS_TYPE_UNIX; #ifdef CONFIG_LINUX - if (!su->sun_path[0]) { + if (salen > sizeof(su->sun_family) && !su->sun_path[0]) { /* Linux abstract socket */ addr->u.q_unix.path = g_strndup(su->sun_path + 1, salen - sizeof(su->sun_family) - 1); @@ -1363,7 +1370,7 @@ socket_sockaddr_to_address_unix(struct sockaddr_storage *sa, } #endif - addr->u.q_unix.path = g_strndup(su->sun_path, sizeof(su->sun_path)); + addr->u.q_unix.path = g_strndup(su->sun_path, salen - sizeof(su->sun_family)); return addr; } #endif /* WIN32 */ -- 2.30.2
