netdev - Re: [PATCH net] net: sched: act

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Date:   Sun, 19 Jan 2020 06:56:38 +0000
From:   Kevin 'ldir' Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
To:     Eric Dumazet <edumazet@...gle.com>
CC:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzkaller@...glegroups.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH net] net: sched: act_ctinfo: fix memory leak



> On 19 Jan 2020, at 04:45, Eric Dumazet <edumazet@...gle.com> wrote:
> 
> Implement a cleanup method to properly free ci->params
> 
> BUG: memory leak
> unreferenced object 0xffff88811746e2c0 (size 64):
>  comm "syz-executor617", pid 7106, jiffies 4294943055 (age 14.250s)
>  hex dump (first 32 bytes):
>    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>    c0 34 60 84 ff ff ff ff 00 00 00 00 00 00 00 00  .4`.............
>  backtrace:
>    [<0000000015aa236f>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
>    [<0000000015aa236f>] slab_post_alloc_hook mm/slab.h:586 [inline]
>    [<0000000015aa236f>] slab_alloc mm/slab.c:3320 [inline]
>    [<0000000015aa236f>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3549
>    [<000000002c946bd1>] kmalloc include/linux/slab.h:556 [inline]
>    [<000000002c946bd1>] kzalloc include/linux/slab.h:670 [inline]
>    [<000000002c946bd1>] tcf_ctinfo_init+0x21a/0x530 net/sched/act_ctinfo.c:236
>    [<0000000086952cca>] tcf_action_init_1+0x400/0x5b0 net/sched/act_api.c:944
>    [<000000005ab29bf8>] tcf_action_init+0x135/0x1c0 net/sched/act_api.c:1000
>    [<00000000392f56f9>] tcf_action_add+0x9a/0x200 net/sched/act_api.c:1410
>    [<0000000088f3c5dd>] tc_ctl_action+0x14d/0x1bb net/sched/act_api.c:1465
>    [<000000006b39d986>] rtnetlink_rcv_msg+0x178/0x4b0 net/core/rtnetlink.c:5424
>    [<00000000fd6ecace>] netlink_rcv_skb+0x61/0x170 net/netlink/af_netlink.c:2477
>    [<0000000047493d02>] rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5442
>    [<00000000bdcf8286>] netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
>    [<00000000bdcf8286>] netlink_unicast+0x223/0x310 net/netlink/af_netlink.c:1328
>    [<00000000fc5b92d9>] netlink_sendmsg+0x2c0/0x570 net/netlink/af_netlink.c:1917
>    [<00000000da84d076>] sock_sendmsg_nosec net/socket.c:639 [inline]
>    [<00000000da84d076>] sock_sendmsg+0x54/0x70 net/socket.c:659
>    [<0000000042fb2eee>] ____sys_sendmsg+0x2d0/0x300 net/socket.c:2330
>    [<000000008f23f67e>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2384
>    [<00000000d838e4f6>] __sys_sendmsg+0x80/0xf0 net/socket.c:2417
>    [<00000000289a9cb1>] __do_sys_sendmsg net/socket.c:2426 [inline]
>    [<00000000289a9cb1>] __se_sys_sendmsg net/socket.c:2424 [inline]
>    [<00000000289a9cb1>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2424
> 
> Fixes: 24ec483cec98 ("net: sched: Introduce act_ctinfo action")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>
> Cc: Kevin 'ldir' Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
> Cc: Cong Wang <xiyou.wangcong@...il.com>
> Cc: Toke Høiland-Jørgensen <toke@...hat.com>
> ---
> net/sched/act_ctinfo.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
> 
> diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c
> index 40038c321b4a970dc940714ccda4b39f0d261d6a..19649623493b158b3008c82ce2409ae80ffa6dc6 100644
> --- a/net/sched/act_ctinfo.c
> +++ b/net/sched/act_ctinfo.c
> @@ -360,6 +360,16 @@ static int tcf_ctinfo_search(struct net *net, struct tc_action **a, u32 index)
> 	return tcf_idr_search(tn, a, index);
> }
> 
> +static void tcf_ctinfo_cleanup(struct tc_action *a)
> +{
> +	struct tcf_ctinfo *ci = to_ctinfo(a);
> +	struct tcf_ctinfo_params *cp;
> +
> +	cp = rcu_dereference_protected(ci->params, 1);
> +	if (cp)
> +		kfree_rcu(cp, rcu);
> +}
> +
> static struct tc_action_ops act_ctinfo_ops = {
> 	.kind	= "ctinfo",
> 	.id	= TCA_ID_CTINFO,
> @@ -367,6 +377,7 @@ static struct tc_action_ops act_ctinfo_ops = {
> 	.act	= tcf_ctinfo_act,
> 	.dump	= tcf_ctinfo_dump,
> 	.init	= tcf_ctinfo_init,
> +	.cleanup= tcf_ctinfo_cleanup,
> 	.walk	= tcf_ctinfo_walker,
> 	.lookup	= tcf_ctinfo_search,
> 	.size	= sizeof(struct tcf_ctinfo),
> --
> 2.25.0.341.g760bfbb309-goog
> 

Oh wow & oops!  Thanks for fixing that.

Acked-by: Kevin 'ldir' Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>

Cheers,

Kevin D-B

gpg: 012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A


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