linux-kernel - Re: [PATCH] net: mac802154: Fix null pointer dereference

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Date:   Thu, 04 Mar 2021 12:23:22 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Alexander Aring <alex.aring@...il.com>
Cc:     Stefan Schmidt <stefan@...enfreihafen.org>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wpan - ML <linux-wpan@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        syzbot+12cf5fbfdeba210a89dd@...kaller.appspotmail.com
Subject: Re: [PATCH] net: mac802154: Fix null pointer dereference

Hi, thanks for your reply!

On Wed, 2021-03-03 at 21:40 -0500, Alexander Aring wrote:
> Hi,
> 
> On Wed, 3 Mar 2021 at 11:28, Pavel Skripkin <paskripkin@...il.com>
> wrote:
> > syzbot found general protection fault in crypto_destroy_tfm()[1].
> > It was caused by wrong clean up loop in llsec_key_alloc().
> > If one of the tfm array members won't be initialized it will cause
> > NULL dereference in crypto_destroy_tfm().
> > 
> > Call Trace:
> >  crypto_free_aead include/crypto/aead.h:191 [inline] [1]
> >  llsec_key_alloc net/mac802154/llsec.c:156 [inline]
> >  mac802154_llsec_key_add+0x9e0/0xcc0 net/mac802154/llsec.c:249
> >  ieee802154_add_llsec_key+0x56/0x80 net/mac802154/cfg.c:338
> >  rdev_add_llsec_key net/ieee802154/rdev-ops.h:260 [inline]
> >  nl802154_add_llsec_key+0x3d3/0x560 net/ieee802154/nl802154.c:1584
> >  genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
> >  genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
> >  genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800
> >  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502
> >  genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
> >  netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
> >  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
> >  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
> >  sock_sendmsg_nosec net/socket.c:654 [inline]
> >  sock_sendmsg+0xcf/0x120 net/socket.c:674
> >  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
> >  ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
> >  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
> >  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > 
> > Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
> > Reported-by: syzbot+12cf5fbfdeba210a89dd@...kaller.appspotmail.com
> > ---
> >  net/mac802154/llsec.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c
> > index 585d33144c33..6709f186f777 100644
> > --- a/net/mac802154/llsec.c
> > +++ b/net/mac802154/llsec.c
> > @@ -151,7 +151,7 @@ llsec_key_alloc(const struct
> > ieee802154_llsec_key *template)
> >  err_tfm0:
> >         crypto_free_sync_skcipher(key->tfm0);
> >  err_tfm:
> > -       for (i = 0; i < ARRAY_SIZE(key->tfm); i++)
> > +       for (; i >= 0; i--)
> >                 if (key->tfm[i])
> 
> I think this need to be:
> 
> if (!IS_ERR_OR_NULL(key->tfm[i]))
> 
> otherwise we still run into issues for the current iterator when
> key->tfm[i] is in range of IS_ERR().

Oh... I got it completly wrong, I'm sorry. If it's still not fixed,
I'll send rigth patch for that.

> 
> - Alex
-- 
With regards,
Pavel Skripkin