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authorEric Dumazet <edumazet@google.com>2023-03-07 16:45:30 +0000
committerJakub Kicinski <kuba@kernel.org>2023-03-08 23:26:03 -0800
commit2aab4b96900272885bc157f8b236abf1cdc02e08 (patch)
treec8bfa0ad825bd20010a26883b29780396aca7a91 /net
parent8f14820801042c221bb9fe51643a2585cac5dec2 (diff)
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')
-rw-r--r--net/unix/af_unix.c10
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++;