netdev - Re: [PATCH] net: ipv4: fix memory leak in netlbl_cipsov4_add

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Message-ID: <CAD-N9QU+nq1AxpBqodZWisT4x=BTjW_S45Yq=ZaaDp1cOi72iA@mail.gmail.com>
Date:   Tue, 8 Jun 2021 10:56:23 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Paul Moore <paul@...l-moore.com>
Cc:     Nanyong Sun <sunnanyong@...wei.com>, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: ipv4: fix memory leak in netlbl_cipsov4_add_std

On Tue, Jun 8, 2021 at 10:30 AM Dongliang Mu <mudongliangabcd@...il.com> wrote:
>
> On Tue, Jun 8, 2021 at 9:57 AM Paul Moore <paul@...l-moore.com> wrote:
> >
> > On Mon, Jun 7, 2021 at 9:19 PM Nanyong Sun <sunnanyong@...wei.com> wrote:
> > >
> > > Reported by syzkaller:
> > > BUG: memory leak
> > > unreferenced object 0xffff888105df7000 (size 64):
> > > comm "syz-executor842", pid 360, jiffies 4294824824 (age 22.546s)
> > > hex dump (first 32 bytes):
> > > 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 00 ................
> > > backtrace:
> > > [<00000000e67ed558>] kmalloc include/linux/slab.h:590 [inline]
> > > [<00000000e67ed558>] kzalloc include/linux/slab.h:720 [inline]
> > > [<00000000e67ed558>] netlbl_cipsov4_add_std net/netlabel/netlabel_cipso_v4.c:145 [inline]
> > > [<00000000e67ed558>] netlbl_cipsov4_add+0x390/0x2340 net/netlabel/netlabel_cipso_v4.c:416
> > > [<0000000006040154>] genl_family_rcv_msg_doit.isra.0+0x20e/0x320 net/netlink/genetlink.c:739
> > > [<00000000204d7a1c>] genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
> > > [<00000000204d7a1c>] genl_rcv_msg+0x2bf/0x4f0 net/netlink/genetlink.c:800
> > > [<00000000c0d6a995>] netlink_rcv_skb+0x134/0x3d0 net/netlink/af_netlink.c:2504
> > > [<00000000d78b9d2c>] genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
> > > [<000000009733081b>] netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
> > > [<000000009733081b>] netlink_unicast+0x4a0/0x6a0 net/netlink/af_netlink.c:1340
> > > [<00000000d5fd43b8>] netlink_sendmsg+0x789/0xc70 net/netlink/af_netlink.c:1929
> > > [<000000000a2d1e40>] sock_sendmsg_nosec net/socket.c:654 [inline]
> > > [<000000000a2d1e40>] sock_sendmsg+0x139/0x170 net/socket.c:674
> > > [<00000000321d1969>] ____sys_sendmsg+0x658/0x7d0 net/socket.c:2350
> > > [<00000000964e16bc>] ___sys_sendmsg+0xf8/0x170 net/socket.c:2404
> > > [<000000001615e288>] __sys_sendmsg+0xd3/0x190 net/socket.c:2433
> > > [<000000004ee8b6a5>] do_syscall_64+0x37/0x90 arch/x86/entry/common.c:47
> > > [<00000000171c7cee>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> > >
> > > The memory of doi_def->map.std pointing is allocated in
> > > netlbl_cipsov4_add_std, but no place has freed it. It should be
> > > freed in cipso_v4_doi_free which frees the cipso DOI resource.
> > >
> > > Fixes: 96cb8e3313c7a ("[NetLabel]: CIPSOv4 and Unlabeled packet integration")
> > > Reported-by: Hulk Robot <hulkci@...wei.com>
> > > Signed-off-by: Nanyong Sun <sunnanyong@...wei.com>
> > > ---
> > >  net/ipv4/cipso_ipv4.c | 1 +
> > >  1 file changed, 1 insertion(+)
> >
> > Nice catch, thanks for fixing this.
> >
> > Acked-by: Paul Moore <paul@...l-moore.com>
> >
> > > diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> > > index d6e3a92841e3..099259fc826a 100644
> > > --- a/net/ipv4/cipso_ipv4.c
> > > +++ b/net/ipv4/cipso_ipv4.c
> > > @@ -471,6 +471,7 @@ void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
> > >                 kfree(doi_def->map.std->lvl.local);
> > >                 kfree(doi_def->map.std->cat.cipso);
> > >                 kfree(doi_def->map.std->cat.local);
> > > +               kfree(doi_def->map.std);
> > >                 break;
> > >         }
> > >         kfree(doi_def);
>
> Hi kernel developers,
>
> I doubt this patch may cause invalid free in other functions where
> map.std is not allocated or initialized, such as
> netlbl_cipsov4_add_local, netlbl_cipsov4_add_pass.
>
> Take netlbl_cipsov4_add_pass as an example, any failure after the
> doi_def allocation failure will go to cipso_v4_doi_free, and free
> doi_def->map.std.

Sorry for the false alarm.

The new added kfree(doi_def->map.std) is under the condition - case
CIPSO_V4_MAP_TRANS. So there will be not invalid free. Sorry about
this.

>
> static int netlbl_cipsov4_add_pass(struct genl_info *info,
>   struct netlbl_audit *audit_info)
> {
> int ret_val;
> struct cipso_v4_doi *doi_def = NULL;
>
> if (!info->attrs[NLBL_CIPSOV4_A_TAGLST])
> return -EINVAL;
>
> doi_def = kmalloc(sizeof(*doi_def), GFP_KERNEL);
> if (doi_def == NULL)
> return -ENOMEM;
> doi_def->type = CIPSO_V4_MAP_PASS;
>
> ret_val = netlbl_cipsov4_add_common(info, doi_def);
> if (ret_val != 0)
> goto add_pass_failure;
>
> ret_val = cipso_v4_doi_add(doi_def, audit_info);
> if (ret_val != 0)
> goto add_pass_failure;
> return 0;
>
> add_pass_failure:
> cipso_v4_doi_free(doi_def);
> return ret_val;
> }
>
> [1] https://elixir.bootlin.com/linux/latest/source/net/netlabel/netlabel_cipso_v4.c#L326
>
> > > --
> > > 2.18.0.huawei.25
> >
> > --
> > paul moore
> > www.paul-moore.com