Messages in this thread | | | From | butt3rflyh4ck <> | Date | Thu, 4 Nov 2021 11:07:16 +0800 | Subject | Re: A kernel-infoleak bug in pppoe_getname() in drivers/net/ppp/pppoe.c |
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Ok, I will check. Oh, you are right.
On Thu, Nov 4, 2021 at 12:53 AM Jakub Kicinski <kuba@kernel.org> wrote: > > On Thu, 4 Nov 2021 00:14:31 +0800 butt3rflyh4ck wrote: > > Hi, I report a kernel-infoleak bug in pppoe_getname()) in > > drivers/net/ppp/pppoe.c. > > And we can call getname ioctl to invoke pppoe_getname(). > > > > ###anaylze > > ``` > > static int pppoe_getname(struct socket *sock, struct sockaddr *uaddr, > > int peer) > > { > > int len = sizeof(struct sockaddr_pppox); > > struct sockaddr_pppox sp; ///---> define a 'sp' in stack but does > > not clear it > > > > sp.sa_family = AF_PPPOX; ///---> sp.sa_family is a short type, just > > But the structure is marked as __packed. > > > 2 byte sizes. > > sp.sa_protocol = PX_PROTO_OE; > > memcpy(&sp.sa_addr.pppoe, &pppox_sk(sock->sk)->pppoe_pa, > > sizeof(struct pppoe_addr)); > > > > memcpy(uaddr, &sp, len); > > > > return len; > > } > > ``` > > There is an anonymous 2-byte hole after sa_family, make sure to clear it. > > > > ###fix > > use memset() to clear the struct sockaddr_pppox sp. > > ``` > > diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c > > index 3619520340b7..fec328ad7202 100644 > > --- a/drivers/net/ppp/pppoe.c > > +++ b/drivers/net/ppp/pppoe.c > > @@ -723,6 +723,11 @@ static int pppoe_getname(struct socket *sock, > > struct sockaddr *uaddr, > > int len = sizeof(struct sockaddr_pppox); > > struct sockaddr_pppox sp; > > > > + /* There is an anonymous 2-byte hole after sa_family, > > + * make sure to clear it. > > + */ > > + memset(&sp, 0, len); > > + > > sp.sa_family = AF_PPPOX; > > sp.sa_protocol = PX_PROTO_OE; > > memcpy(&sp.sa_addr.pppoe, &pppox_sk(sock->sk)->pppoe_pa, > > ``` > > The attachment is a patch. >
-- Active Defense Lab of Venustech
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