diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2022-10-06 21:53:45 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-10-13 03:50:37 +0300 |
| commit | 3c52c6bb831f6335c176a0fc7214e26f43adbd11 (patch) | |
| tree | b795ed7e3b57b136b39305817d398481300a7e2b | |
| parent | 3a732b46736cd8a29092e4b0b1a9ba83e672bf89 (diff) | |
| download | linux-3c52c6bb831f6335c176a0fc7214e26f43adbd11.tar.xz | |
tcp/udp: Fix memory leak in ipv6_renew_options().
syzbot reported a memory leak [0] related to IPV6_ADDRFORM.
The scenario is that while one thread is converting an IPv6 socket into
IPv4 with IPV6_ADDRFORM, another thread calls do_ipv6_setsockopt() and
allocates memory to inet6_sk(sk)->XXX after conversion.
Then, the converted sk with (tcp|udp)_prot never frees the IPv6 resources,
which inet6_destroy_sock() should have cleaned up.
setsockopt(IPV6_ADDRFORM) setsockopt(IPV6_DSTOPTS)
+-----------------------+ +----------------------+
- do_ipv6_setsockopt(sk, ...)
- sockopt_lock_sock(sk) - do_ipv6_setsockopt(sk, ...)
- lock_sock(sk) ^._ called via tcpv6_prot
- WRITE_ONCE(sk->sk_prot, &tcp_prot) before WRITE_ONCE()
- xchg(&np->opt, NULL)
- txopt_put(opt)
- sockopt_release_sock(sk)
- release_sock(sk) - sockopt_lock_sock(sk)
- lock_sock(sk)
- ipv6_set_opt_hdr(sk, ...)
- ipv6_update_options(sk, opt)
- xchg(&inet6_sk(sk)->opt, opt)
^._ opt is never freed.
- sockopt_release_sock(sk)
- release_sock(sk)
Since IPV6_DSTOPTS allocates options under lock_sock(), we can avoid this
memory leak by testing whether sk_family is changed by IPV6_ADDRFORM after
acquiring the lock.
This issue exists from the initial commit between IPV6_ADDRFORM and
IPV6_PKTOPTIONS.
[0]:
BUG: memory leak
unreferenced object 0xffff888009ab9f80 (size 96):
comm "syz-executor583", pid 328, jiffies 4294916198 (age 13.034s)
hex dump (first 32 bytes):
01 00 00 00 48 00 00 00 08 00 00 00 00 00 00 00 ....H...........
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<000000002ee98ae1>] kmalloc include/linux/slab.h:605 [inline]
[<000000002ee98ae1>] sock_kmalloc+0xb3/0x100 net/core/sock.c:2566
[<0000000065d7b698>] ipv6_renew_options+0x21e/0x10b0 net/ipv6/exthdrs.c:1318
[<00000000a8c756d7>] ipv6_set_opt_hdr net/ipv6/ipv6_sockglue.c:354 [inline]
[<00000000a8c756d7>] do_ipv6_setsockopt.constprop.0+0x28b7/0x4350 net/ipv6/ipv6_sockglue.c:668
[<000000002854d204>] ipv6_setsockopt+0xdf/0x190 net/ipv6/ipv6_sockglue.c:1021
[<00000000e69fdcf8>] tcp_setsockopt+0x13b/0x2620 net/ipv4/tcp.c:3789
[<0000000090da4b9b>] __sys_setsockopt+0x239/0x620 net/socket.c:2252
[<00000000b10d192f>] __do_sys_setsockopt net/socket.c:2263 [inline]
[<00000000b10d192f>] __se_sys_setsockopt net/socket.c:2260 [inline]
[<00000000b10d192f>] __x64_sys_setsockopt+0xbe/0x160 net/socket.c:2260
[<000000000a80d7aa>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<000000000a80d7aa>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80
[<000000004562b5c6>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/ipv6/ipv6_sockglue.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 2d2f4dd9e5df..408345fc4c5c 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -419,6 +419,12 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname, rtnl_lock(); sockopt_lock_sock(sk); + /* Another thread has converted the socket into IPv4 with + * IPV6_ADDRFORM concurrently. + */ + if (unlikely(sk->sk_family != AF_INET6)) + goto unlock; + switch (optname) { case IPV6_ADDRFORM: @@ -994,6 +1000,7 @@ done: break; } +unlock: sockopt_release_sock(sk); if (needs_rtnl) rtnl_unlock(); |