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Message-ID: <20160307194406.GH31743@localhost.localdomain>
Date: Mon, 7 Mar 2016 16:44:06 -0300
From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Neil Horman <nhorman@...driver.com>,
Vlad Yasevich <vyasevich@...il.com>,
netdev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
David Miller <davem@...emloft.net>,
syzkaller <syzkaller@...glegroups.com>,
Kostya Serebryany <kcc@...gle.com>,
Alexander Potapenko <glider@...gle.com>,
Sasha Levin <sasha.levin@...cle.com>,
Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net] sctp: fix copying more bytes than expected in
sctp_add_bind_addr
On Tue, Jan 26, 2016 at 02:28:48PM +0100, Dmitry Vyukov wrote:
> On Mon, Jan 25, 2016 at 6:52 PM, Marcelo Ricardo Leitner
> <marcelo.leitner@...il.com> wrote:
> > Great. Dmitry, please give this a run. Local tests looked good but who
> > knows what syzkaller may find.
>
> Now running with this patch.
Hi Dmitry, do you remember if this one succeeded?
> > Thanks
> >
> > --8<--
> >
> > Dmitry reported that sctp_add_bind_addr may read more bytes than
> > expected in case the parameter is a IPv4 addr supplied by the user
> > through calls such as sctp_bindx_add(), because it always copies
> > sizeof(union sctp_addr) while the buffer may be just a struct
> > sockaddr_in, which is smaller.
> >
> > This patch then fixes it by limiting the memcpy to the min between the
> > union size and a (new parameter) provided addr size. Where possible this
> > parameter still is the size of that union, except for reading from
> > user-provided buffers, which then it accounts for protocol type.
> >
> > Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> > Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
> > ---
> > include/net/sctp/structs.h | 2 +-
> > net/sctp/bind_addr.c | 14 ++++++++------
> > net/sctp/protocol.c | 1 +
> > net/sctp/sm_make_chunk.c | 2 +-
> > net/sctp/socket.c | 5 +++--
> > 5 files changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> > index 20e72129be1ce0063eeafcbaadcee1f37e0c614c..97ba8a8c466f5c50bdc87ec578792e56553baa91 100644
> > --- a/include/net/sctp/structs.h
> > +++ b/include/net/sctp/structs.h
> > @@ -1099,7 +1099,7 @@ int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
> > const struct sctp_bind_addr *src,
> > gfp_t gfp);
> > int sctp_add_bind_addr(struct sctp_bind_addr *, union sctp_addr *,
> > - __u8 addr_state, gfp_t gfp);
> > + int new_size, __u8 addr_state, gfp_t gfp);
> > int sctp_del_bind_addr(struct sctp_bind_addr *, union sctp_addr *);
> > int sctp_bind_addr_match(struct sctp_bind_addr *, const union sctp_addr *,
> > struct sctp_sock *);
> > diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c
> > index 871cdf9567e6bc9c13cb1077dc6866a67e6e4367..80129d10a0af9c33e7348b79d010b9e5e948e584 100644
> > --- a/net/sctp/bind_addr.c
> > +++ b/net/sctp/bind_addr.c
> > @@ -111,7 +111,8 @@ int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
> > dest->port = src->port;
> >
> > list_for_each_entry(addr, &src->address_list, list) {
> > - error = sctp_add_bind_addr(dest, &addr->a, 1, gfp);
> > + error = sctp_add_bind_addr(dest, &addr->a, sizeof(addr->a),
> > + 1, gfp);
> > if (error < 0)
> > break;
> > }
> > @@ -150,7 +151,7 @@ void sctp_bind_addr_free(struct sctp_bind_addr *bp)
> >
> > /* Add an address to the bind address list in the SCTP_bind_addr structure. */
> > int sctp_add_bind_addr(struct sctp_bind_addr *bp, union sctp_addr *new,
> > - __u8 addr_state, gfp_t gfp)
> > + int new_size, __u8 addr_state, gfp_t gfp)
> > {
> > struct sctp_sockaddr_entry *addr;
> >
> > @@ -159,7 +160,7 @@ int sctp_add_bind_addr(struct sctp_bind_addr *bp, union sctp_addr *new,
> > if (!addr)
> > return -ENOMEM;
> >
> > - memcpy(&addr->a, new, sizeof(*new));
> > + memcpy(&addr->a, new, min_t(size_t, sizeof(*new), new_size));
> >
> > /* Fix up the port if it has not yet been set.
> > * Both v4 and v6 have the port at the same offset.
> > @@ -291,7 +292,8 @@ int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw_addr_list,
> > }
> >
> > af->from_addr_param(&addr, rawaddr, htons(port), 0);
> > - retval = sctp_add_bind_addr(bp, &addr, SCTP_ADDR_SRC, gfp);
> > + retval = sctp_add_bind_addr(bp, &addr, sizeof(addr),
> > + SCTP_ADDR_SRC, gfp);
> > if (retval) {
> > /* Can't finish building the list, clean up. */
> > sctp_bind_addr_clean(bp);
> > @@ -453,8 +455,8 @@ static int sctp_copy_one_addr(struct net *net, struct sctp_bind_addr *dest,
> > (((AF_INET6 == addr->sa.sa_family) &&
> > (flags & SCTP_ADDR6_ALLOWED) &&
> > (flags & SCTP_ADDR6_PEERSUPP))))
> > - error = sctp_add_bind_addr(dest, addr, SCTP_ADDR_SRC,
> > - gfp);
> > + error = sctp_add_bind_addr(dest, addr, sizeof(addr),
> > + SCTP_ADDR_SRC, gfp);
> > }
> >
> > return error;
> > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> > index ab0d538a74ed593571cfaef02cd1bb7ce872abe6..2fb609008311f51344704d82f21b4de9f08253da 100644
> > --- a/net/sctp/protocol.c
> > +++ b/net/sctp/protocol.c
> > @@ -214,6 +214,7 @@ int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
> > (copy_flags & SCTP_ADDR6_ALLOWED) &&
> > (copy_flags & SCTP_ADDR6_PEERSUPP)))) {
> > error = sctp_add_bind_addr(bp, &addr->a,
> > + sizeof(addr->a),
> > SCTP_ADDR_SRC, GFP_ATOMIC);
> > if (error)
> > goto end_copy;
> > diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> > index 5d6a03fad3789a12290f5f14c5a7efa69c98f41a..1b91e9760fe514db6d89457e1d5da9e02800745e 100644
> > --- a/net/sctp/sm_make_chunk.c
> > +++ b/net/sctp/sm_make_chunk.c
> > @@ -1830,7 +1830,7 @@ no_hmac:
> > /* Also, add the destination address. */
> > if (list_empty(&retval->base.bind_addr.address_list)) {
> > sctp_add_bind_addr(&retval->base.bind_addr, &chunk->dest,
> > - SCTP_ADDR_SRC, GFP_ATOMIC);
> > + sizeof(chunk->dest), SCTP_ADDR_SRC, GFP_ATOMIC);
> > }
> >
> > retval->next_tsn = retval->c.initial_tsn;
> > diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> > index 5ca2ebfe0be83882fcb841de6fa8029b6455ef85..213be3821a1d49e0c469c4ad4e9ff055a03205c5 100644
> > --- a/net/sctp/socket.c
> > +++ b/net/sctp/socket.c
> > @@ -386,7 +386,8 @@ static int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
> > /* Add the address to the bind address list.
> > * Use GFP_ATOMIC since BHs will be disabled.
> > */
> > - ret = sctp_add_bind_addr(bp, addr, SCTP_ADDR_SRC, GFP_ATOMIC);
> > + ret = sctp_add_bind_addr(bp, addr, af->sockaddr_len,
> > + SCTP_ADDR_SRC, GFP_ATOMIC);
> >
> > /* Copy back into socket for getsockname() use. */
> > if (!ret) {
> > @@ -576,7 +577,7 @@ static int sctp_send_asconf_add_ip(struct sock *sk,
> > addr = addr_buf;
> > af = sctp_get_af_specific(addr->v4.sin_family);
> > memcpy(&saveaddr, addr, af->sockaddr_len);
> > - retval = sctp_add_bind_addr(bp, &saveaddr,
> > + retval = sctp_add_bind_addr(bp, &saveaddr, sizeof(saveaddr),
> > SCTP_ADDR_NEW, GFP_ATOMIC);
> > addr_buf += af->sockaddr_len;
> > }
> > --
> > 2.5.0
> >
> --
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