https://bugs.kde.org/show_bug.cgi?id=457094
Bug ID: 457094
Summary: Unititialized memory false positive -
ioctl(SIOCSIFADDR) with IPv6
Product: valgrind
Version: 3.19.0
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: jsew...@acm.org
Reporter: arequip...@gmail.com
Target Milestone: ---
It seems that Valgrind does not know about struct in6_ifreq, which is used when
manipulating IPv6 addresses with ioctl(). (See netdevice(7).) Thus, the
following code causes Valgrind to incorrectly detect use of unitialized memory:
static void ipou_set_tun_ip6(void)
{
struct in6_ifreq ifr6;
memset(&ifr6, 0, sizeof ifr6);
ifr6.ifr6_addr = ipou_tun_addr6;
ifr6.ifr6_prefixlen = ipou_tun_pfx6;
ifr6.ifr6_ifindex = ipou_tun_index;
if (ioctl(ipou_socket_fd, SIOCSIFADDR, &ifr6) < 0)
IPOU_FATAL("ioctl failed: SIOCSIFADDR: %m");
}
(ipou_socket_fd is an AF_INET6 socket.)
The error reported is:
==12298== Syscall param ioctl(SIOCSIF*ADDR) points to uninitialised byte(s)
==12298== at 0x499776F: ioctl (in /usr/lib64/libc.so.6)
==12298== by 0x4082C1: ipou_set_tun_ip6 (tun.c:70)
==12298== by 0x4085EF: ipou_tun_setup (tun.c:123)
==12298== by 0x402991: ipou_client_hello (client.c:99)
==12298== by 0x4029CF: ipou_client_setup (client.c:110)
==12298== by 0x405765: main (main.c:51)
==12298== Address 0x1fff000298 is on thread 1's stack
==12298== in frame #1, created by ipou_set_tun_ip6 (tun.c:62)
==12298==
The error can be suppressed by ensuring that the initialized block passed to
ioctl() is at least as large as a struct ifreq.
static void ipou_set_tun_ip6(void)
{
union { struct in6_ifreq ifr6; struct ifreq ifr; } req;
memset(&req, 0, sizeof req);
req.ifr6.ifr6_addr = ipou_tun_addr6;
req.ifr6.ifr6_prefixlen = ipou_tun_pfx6;
req.ifr6.ifr6_ifindex = ipou_tun_index;
if (ioctl(ipou_socket_fd, SIOCSIFADDR, &req.ifr6) < 0)
IPOU_FATAL("ioctl failed: SIOCSIFADDR: %m");
}
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