From decb705e01a5d325c9876b9674043cde4b54f0db Mon Sep 17 00:00:00 2001 From: Ilya Maximets Date: Tue, 23 Jul 2019 15:08:10 +0300 Subject: libbpf: fix using uninitialized ioctl results 'channels.max_combined' initialized only on ioctl success and errno is only valid on ioctl failure. The code doesn't produce any runtime issues, but makes memory sanitizers angry: Conditional jump or move depends on uninitialised value(s) at 0x55C056F: xsk_get_max_queues (xsk.c:336) by 0x55C05B2: xsk_create_bpf_maps (xsk.c:354) by 0x55C089F: xsk_setup_xdp_prog (xsk.c:447) by 0x55C0E57: xsk_socket__create (xsk.c:601) Uninitialised value was created by a stack allocation at 0x55C04CD: xsk_get_max_queues (xsk.c:318) Additionally fixed warning on uninitialized bytes in ioctl arguments: Syscall param ioctl(SIOCETHTOOL) points to uninitialised byte(s) at 0x648D45B: ioctl (in /usr/lib64/libc-2.28.so) by 0x55C0546: xsk_get_max_queues (xsk.c:330) by 0x55C05B2: xsk_create_bpf_maps (xsk.c:354) by 0x55C089F: xsk_setup_xdp_prog (xsk.c:447) by 0x55C0E57: xsk_socket__create (xsk.c:601) Address 0x1ffefff378 is on thread 1's stack in frame #1, created by xsk_get_max_queues (xsk.c:318) Uninitialised value was created by a stack allocation at 0x55C04CD: xsk_get_max_queues (xsk.c:318) CC: Magnus Karlsson Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets") Signed-off-by: Ilya Maximets Acked-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/xsk.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'tools/lib/bpf/xsk.c') diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index 5007b5d4fd2c..e02025bbe36d 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -317,15 +317,14 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk) static int xsk_get_max_queues(struct xsk_socket *xsk) { - struct ethtool_channels channels; - struct ifreq ifr; + struct ethtool_channels channels = { .cmd = ETHTOOL_GCHANNELS }; + struct ifreq ifr = {}; int fd, err, ret; fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) return -errno; - channels.cmd = ETHTOOL_GCHANNELS; ifr.ifr_data = (void *)&channels; strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1); ifr.ifr_name[IFNAMSIZ - 1] = '\0'; @@ -335,7 +334,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk) goto out; } - if (channels.max_combined == 0 || errno == EOPNOTSUPP) + if (err || channels.max_combined == 0) /* If the device says it has no channels, then all traffic * is sent to a single stream, so max queues = 1. */ -- cgit v1.2.3 From cb8ffde5694ae5fffb456eae932aac442aa3a207 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 24 Jul 2019 14:47:53 -0700 Subject: libbpf: silence GCC8 warning about string truncation Despite a proper NULL-termination after strncpy(..., ..., IFNAMSIZ - 1), GCC8 still complains about *expected* string truncation: xsk.c:330:2: error: 'strncpy' output may be truncated copying 15 bytes from a string of length 15 [-Werror=stringop-truncation] strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1); This patch gets rid of the issue altogether by using memcpy instead. There is no performance regression, as strncpy will still copy and fill all of the bytes anyway. v1->v2: - rebase against bpf tree. Cc: Magnus Karlsson Signed-off-by: Andrii Nakryiko Acked-by: Magnus Karlsson Acked-by: Song Liu Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/xsk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/lib/bpf/xsk.c') diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index e02025bbe36d..680e63066cf3 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -326,7 +326,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk) return -errno; ifr.ifr_data = (void *)&channels; - strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1); + memcpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1); ifr.ifr_name[IFNAMSIZ - 1] = '\0'; err = ioctl(fd, SIOCETHTOOL, &ifr); if (err && errno != EOPNOTSUPP) { @@ -516,7 +516,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname, err = -errno; goto out_socket; } - strncpy(xsk->ifname, ifname, IFNAMSIZ - 1); + memcpy(xsk->ifname, ifname, IFNAMSIZ - 1); xsk->ifname[IFNAMSIZ - 1] = '\0'; err = xsk_set_xdp_socket_config(&xsk->config, usr_config); -- cgit v1.2.3