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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: 6d0bfe2261 ("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>
e27326009a