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Date: Mon, 1 Apr 2019 10:43:55 +0200 From: Alexander Potapenko <glider@...gle.com> To: Xin Long <lucien.xin@...il.com> Cc: network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org, David Miller <davem@...emloft.net>, Marcelo Ricardo Leitner <marcelo.leitner@...il.com>, Neil Horman <nhorman@...driver.com>, syzkaller <syzkaller@...glegroups.com> Subject: Re: [PATCH net] sctp: initialize _pad of sockaddr_in before copying to user memory On Sun, Mar 31, 2019 at 10:58 AM Xin Long <lucien.xin@...il.com> wrote: > > Syzbot report a kernel-infoleak: > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 > Call Trace: > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 > copy_to_user include/linux/uaccess.h:174 [inline] > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline] > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562 > ... > Uninit was stored to memory at: > sctp_transport_init net/sctp/transport.c:61 [inline] > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115 > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637 > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline] > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361 > ... > Bytes 8-15 of 16 are uninitialized > > It was caused by that th _pad field (the 8-15 bytes) of a v4 addr (saved in > struct sockaddr_in) wasn't initialized, but directly copied to user memory > in sctp_getsockopt_peer_addrs(). > > So fix it by calling memset(addr->v4.sin_zero, 0, 8) to initialize _pad of > sockaddr_in before copying it to user memory in sctp_v4_addr_to_user(), as > sctp_v6_addr_to_user() does. > > Reported-by: syzbot+86b5c7c236a22616a72f@...kaller.appspotmail.com > Signed-off-by: Xin Long <lucien.xin@...il.com> Tested-by: Alexander Potapenko <glider@...gle.com> > --- > net/sctp/protocol.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c > index 6abc8b2..951afde 100644 > --- a/net/sctp/protocol.c > +++ b/net/sctp/protocol.c > @@ -600,6 +600,7 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk, > static int sctp_v4_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr) > { > /* No address mapping for V4 sockets */ > + memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero)); > return sizeof(struct sockaddr_in); > } > > -- > 2.1.0 > > -- > You received this message because you are subscribed to the Google Groups "syzkaller" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@...glegroups.com. > For more options, visit https://groups.google.com/d/optout. -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
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