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| author | Eric Dumazet <edumazet@google.com> | 2023-03-07 16:45:30 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-03-08 23:26:03 -0800 |
| commit | 2aab4b96900272885bc157f8b236abf1cdc02e08 (patch) | |
| tree | c8bfa0ad825bd20010a26883b29780396aca7a91 /net/unix | |
| parent | 8f14820801042c221bb9fe51643a2585cac5dec2 (diff) | |
| download | lwn-2aab4b96900272885bc157f8b236abf1cdc02e08.tar.gz lwn-2aab4b96900272885bc157f8b236abf1cdc02e08.zip | |
af_unix: fix struct pid leaks in OOB support
syzbot reported struct pid leak [1].
Issue is that queue_oob() calls maybe_add_creds() which potentially
holds a reference on a pid.
But skb->destructor is not set (either directly or by calling
unix_scm_to_skb())
This means that subsequent kfree_skb() or consume_skb() would leak
this reference.
In this fix, I chose to fully support scm even for the OOB message.
[1]
BUG: memory leak
unreferenced object 0xffff8881053e7f80 (size 128):
comm "syz-executor242", pid 5066, jiffies 4294946079 (age 13.220s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff812ae26a>] alloc_pid+0x6a/0x560 kernel/pid.c:180
[<ffffffff812718df>] copy_process+0x169f/0x26c0 kernel/fork.c:2285
[<ffffffff81272b37>] kernel_clone+0xf7/0x610 kernel/fork.c:2684
[<ffffffff812730cc>] __do_sys_clone+0x7c/0xb0 kernel/fork.c:2825
[<ffffffff849ad699>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff849ad699>] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
[<ffffffff84a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: 314001f0bf92 ("af_unix: Add OOB support")
Reported-by: syzbot+7699d9e5635c10253a27@syzkaller.appspotmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Rao Shoaib <rao.shoaib@oracle.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230307164530.771896-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/unix')
| -rw-r--r-- | net/unix/af_unix.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 347122c3575e..0b0f18ecce44 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2105,7 +2105,8 @@ out: #define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768)) #if IS_ENABLED(CONFIG_AF_UNIX_OOB) -static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other) +static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other, + struct scm_cookie *scm, bool fds_sent) { struct unix_sock *ousk = unix_sk(other); struct sk_buff *skb; @@ -2116,6 +2117,11 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other if (!skb) return err; + err = unix_scm_to_skb(scm, skb, !fds_sent); + if (err < 0) { + kfree_skb(skb); + return err; + } skb_put(skb, 1); err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, 1); @@ -2243,7 +2249,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, #if IS_ENABLED(CONFIG_AF_UNIX_OOB) if (msg->msg_flags & MSG_OOB) { - err = queue_oob(sock, msg, other); + err = queue_oob(sock, msg, other, &scm, fds_sent); if (err) goto out_err; sent++; |