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Commit 4db428a7 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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soreuseport: fix mem leak in reuseport_add_sock() 



reuseport_add_sock() needs to deal with attaching a socket having
its own sk_reuseport_cb, after a prior
setsockopt(SO_ATTACH_REUSEPORT_?BPF)

Without this fix, not only a WARN_ONCE() was issued, but we were also
leaking memory.

Thanks to sysbot and Eric Biggers for providing us nice C repros.

------------[ cut here ]------------
socket already in reuseport group
WARNING: CPU: 0 PID: 3496 at net/core/sock_reuseport.c:119  
reuseport_add_sock+0x742/0x9b0 net/core/sock_reuseport.c:117
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 3496 Comm: syzkaller869503 Not tainted 4.15.0-rc6+ #245
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x211/0x2d0 lib/bug.c:184
  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
  fixup_bug arch/x86/kernel/traps.c:247 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
  invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1079

Fixes: ef456144 ("soreuseport: define reuseport groups")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatar <syzbot+c0ea2226f77a42936bf7@syzkaller.appspotmail.com>
Acked-by: default avatarCraig Gallek <kraig@google.com>

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cfabb177

net/core/sock_reuseport.c

+20 −15
Original line number Diff line number Diff line
@@ -94,6 +94,16 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) 
	return more_reuse;

}



static void reuseport_free_rcu(struct rcu_head *head)

{

	struct sock_reuseport *reuse;



	reuse = container_of(head, struct sock_reuseport, rcu);

	if (reuse->prog)

		bpf_prog_destroy(reuse->prog);

	kfree(reuse);

}



/**

 *  reuseport_add_sock - Add a socket to the reuseport group of another.

 *  @sk:  New socket to add to the group.
@@ -102,7 +112,7 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) 
 */

int reuseport_add_sock(struct sock *sk, struct sock *sk2)

{

	struct sock_reuseport *reuse;

	struct sock_reuseport *old_reuse, *reuse;



	if (!rcu_access_pointer(sk2->sk_reuseport_cb)) {

		int err = reuseport_alloc(sk2);
@@ -113,10 +123,13 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2) 


	spin_lock_bh(&reuseport_lock);

	reuse = rcu_dereference_protected(sk2->sk_reuseport_cb,

					  lockdep_is_held(&reuseport_lock)),

	WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb,

					    lockdep_is_held(&reuseport_lock)),

		  "socket already in reuseport group");

					  lockdep_is_held(&reuseport_lock));

	old_reuse = rcu_dereference_protected(sk->sk_reuseport_cb,

					     lockdep_is_held(&reuseport_lock));

	if (old_reuse && old_reuse->num_socks != 1) {

		spin_unlock_bh(&reuseport_lock);

		return -EBUSY;

	}



	if (reuse->num_socks == reuse->max_socks) {

		reuse = reuseport_grow(reuse);
@@ -134,19 +147,11 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2) 


	spin_unlock_bh(&reuseport_lock);



	if (old_reuse)

		call_rcu(&old_reuse->rcu, reuseport_free_rcu);

	return 0;

}



static void reuseport_free_rcu(struct rcu_head *head)

{

	struct sock_reuseport *reuse;



	reuse = container_of(head, struct sock_reuseport, rcu);

	if (reuse->prog)

		bpf_prog_destroy(reuse->prog);

	kfree(reuse);

}



void reuseport_detach_sock(struct sock *sk)

{

	struct sock_reuseport *reuse;