Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit decb705e authored by Ilya Maximets's avatar Ilya Maximets Committed by Alexei Starovoitov
Browse files

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 <magnus.karlsson@intel.com>
Fixes: 1cad0788 ("libbpf: add support for using AF_XDP sockets")
Signed-off-by: default avatarIlya Maximets <i.maximets@samsung.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 7c8b87f0

tools/lib/bpf/xsk.c

+3 −4
Original line number Diff line number Diff line
@@ -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.

		 */