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soreuseport: fix mem leak in reuseport_add_sock()

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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: ef456144da ("soreuseport: define reuseport groups")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot+c0ea2226f77a42936bf7@syzkaller.appspotmail.com
Acked-by: Craig Gallek <kraig@google.com>

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-02-02 10:27:27 -08:00 committed by David S. Miller
parent cfabb1779d
commit 4db428a7c9
1 changed files with 20 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
net/core/sock_reuseport.c
View File

@ -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;