From: Kuniyuki Iwashima kuniyu@amazon.com
commit e27326009a3d247b831eda38878c777f6f4eb3d1 upstream.
When we close ping6 sockets, some resources are left unfreed because pingv6_prot is missing sk->sk_prot->destroy(). As reported by syzbot [0], just three syscalls leak 96 bytes and easily cause OOM.
struct ipv6_sr_hdr *hdr; char data[24] = {0}; int fd;
hdr = (struct ipv6_sr_hdr *)data; hdr->hdrlen = 2; hdr->type = IPV6_SRCRT_TYPE_4;
fd = socket(AF_INET6, SOCK_DGRAM, NEXTHDR_ICMP); setsockopt(fd, IPPROTO_IPV6, IPV6_RTHDR, data, 24); close(fd);
To fix memory leaks, let's add a destroy function.
Note the socket() syscall checks if the GID is within the range of net.ipv4.ping_group_range. The default value is [1, 0] so that no GID meets the condition (1 <= GID <= 0). Thus, the local DoS does not succeed until we change the default value. However, at least Ubuntu/Fedora/RHEL loosen it.
$ cat /usr/lib/sysctl.d/50-default.conf ... -net.ipv4.ping_group_range = 0 2147483647
Also, there could be another path reported with these options, and some of them require CAP_NET_RAW.
setsockopt IPV6_ADDRFORM (inet6_sk(sk)->pktoptions) IPV6_RECVPATHMTU (inet6_sk(sk)->rxpmtu) IPV6_HOPOPTS (inet6_sk(sk)->opt) IPV6_RTHDRDSTOPTS (inet6_sk(sk)->opt) IPV6_RTHDR (inet6_sk(sk)->opt) IPV6_DSTOPTS (inet6_sk(sk)->opt) IPV6_2292PKTOPTIONS (inet6_sk(sk)->opt)
getsockopt IPV6_FLOWLABEL_MGR (inet6_sk(sk)->ipv6_fl_list)
For the record, I left a different splat with syzbot's one.
unreferenced object 0xffff888006270c60 (size 96): comm "repro2", pid 231, jiffies 4294696626 (age 13.118s) hex dump (first 32 bytes): 01 00 00 00 44 00 00 00 00 00 00 00 00 00 00 00 ....D........... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000f6bc7ea9>] sock_kmalloc (net/core/sock.c:2564 net/core/sock.c:2554) [<000000006d699550>] do_ipv6_setsockopt.constprop.0 (net/ipv6/ipv6_sockglue.c:715) [<00000000c3c3b1f5>] ipv6_setsockopt (net/ipv6/ipv6_sockglue.c:1024) [<000000007096a025>] __sys_setsockopt (net/socket.c:2254) [<000000003a8ff47b>] __x64_sys_setsockopt (net/socket.c:2265 net/socket.c:2262 net/socket.c:2262) [<000000007c409dcb>] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) [<00000000e939c4a9>] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
[0]: https://syzkaller.appspot.com/bug?extid=a8430774139ec3ab7176
Fixes: 6d0bfe226116 ("net: ipv6: Add IPv6 support to the ping socket.") Reported-by: syzbot+a8430774139ec3ab7176@syzkaller.appspotmail.com Reported-by: Ayushman Dutta ayudutta@amazon.com Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: David Ahern dsahern@kernel.org Reviewed-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20220728012220.46918-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/ping.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/net/ipv6/ping.c +++ b/net/ipv6/ping.c @@ -27,6 +27,11 @@ #include <linux/proc_fs.h> #include <net/ping.h>
+static void ping_v6_destroy(struct sock *sk) +{ + inet6_destroy_sock(sk); +} + /* Compatibility glue so we can support IPv6 when it's compiled as a module */ static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len) @@ -170,6 +175,7 @@ struct proto pingv6_prot = { .owner = THIS_MODULE, .init = ping_init_sock, .close = ping_close, + .destroy = ping_v6_destroy, .connect = ip6_datagram_connect_v6_only, .disconnect = __udp_disconnect, .setsockopt = ipv6_setsockopt,