Re: [PATCH rdma-rc] RDMA/cma: Clear all multicast request fields

Leon Romanovsky
2022-01-06T18:25:03Z

On Thu, Jan 06, 2022 at 01:39:41PM -0400, Jason Gunthorpe wrote:
> On Thu, Jan 06, 2022 at 03:15:07PM +0200, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > The ib->rec.qkey field is accessed without being initialized.
> > Clear the ib_sa_multicast struct to fix the following syzkaller error/.
> >
> > =====================================================
> > BUG: KMSAN: uninit-value in cma_set_qkey drivers/infiniband/core/cma.c:510 [inline]
> > BUG: KMSAN: uninit-value in cma_make_mc_event+0xb73/0xe00 drivers/infiniband/core/cma.c:4570
> > cma_set_qkey drivers/infiniband/core/cma.c:510 [inline]
> > cma_make_mc_event+0xb73/0xe00 drivers/infiniband/core/cma.c:4570
> > cma_iboe_join_multicast drivers/infiniband/core/cma.c:4782 [inline]
> > rdma_join_multicast+0x2b83/0x30a0 drivers/infiniband/core/cma.c:4814
> > ucma_process_join+0xa76/0xf60 drivers/infiniband/core/ucma.c:1479
> > ucma_join_multicast+0x1e3/0x250 drivers/infiniband/core/ucma.c:1546
> > ucma_write+0x639/0x6d0 drivers/infiniband/core/ucma.c:1732
> > vfs_write+0x8ce/0x2030 fs/read_write.c:588
> > ksys_write+0x28c/0x520 fs/read_write.c:643
> > __do_sys_write fs/read_write.c:655 [inline]
> > __se_sys_write fs/read_write.c:652 [inline]
> > __ia32_sys_write+0xdb/0x120 fs/read_write.c:652
> > do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
> > __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
> > do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
> > do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
> > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
> >
> > Local variable ib.i created at:
> > cma_iboe_join_multicast drivers/infiniband/core/cma.c:4737 [inline]
> > rdma_join_multicast+0x586/0x30a0 drivers/infiniband/core/cma.c:4814
> > ucma_process_join+0xa76/0xf60 drivers/infiniband/core/ucma.c:1479
> >
> > CPU: 0 PID: 29874 Comm: syz-executor.3 Not tainted 5.16.0-rc3-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > =====================================================
> >
> > Fixes: b5de0c60cc30 ("RDMA/cma: Fix use after free race in roce multicast join")
> > Reported-by: syzbot+8fcbb77276d43cc8b693@syzkaller.appspotmail.com
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > drivers/infiniband/core/cma.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> > index 69c9a12dd14e..9c53e1e7de50 100644
> > +++ b/drivers/infiniband/core/cma.c
> > @@ -4737,7 +4737,7 @@ static int cma_iboe_join_multicast(struct rdma_id_private *id_priv,
> > int err = 0;
> > struct sockaddr *addr = (struct sockaddr *)&mc->addr;
> > struct net_device *ndev = NULL;
> > - struct ib_sa_multicast ib;
> > + struct ib_sa_multicast ib = {};
> > enum ib_gid_type gid_type;
> > bool send_only;
>
> We shouldn't be able to join anything except a RDMA_PS_UDP to a
> multicast in the first place:
>
> if (id_priv->id.ps == RDMA_PS_UDP)
> ib.rec.qkey = cpu_to_be32(RDMA_UDP_QKEY);
>
> Multicast RC/etc is meaningless. So I guess it should be like this:

Strange that we don't have repro for such deterministic flow.

>
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -4744,7 +4744,7 @@ static int cma_iboe_join_multicast(struct rdma_id_private *id_priv,
>
> send_only = mc->join_state == BIT(SENDONLY_FULLMEMBER_JOIN);
>
> - if (cma_zero_addr(addr))
> + if (cma_zero_addr(addr) || id_priv->id.ps != RDMA_PS_UDP)
> return -EINVAL;
>
> gid_type = id_priv->cma_dev->default_gid_type[id_priv->id.port_num -
> @@ -4752,8 +4752,7 @@ static int cma_iboe_join_multicast(struct rdma_id_private *id_priv,
> cma_iboe_set_mgid(addr, &ib.rec.mgid, gid_type);
>
> ib.rec.pkey = cpu_to_be16(0xffff);
> - if (id_priv->id.ps == RDMA_PS_UDP)
> - ib.rec.qkey = cpu_to_be32(RDMA_UDP_QKEY);
> + ib.rec.qkey = cpu_to_be32(RDMA_UDP_QKEY);
>
> if (dev_addr->bound_dev_if)
> ndev = dev_get_by_index(dev_addr->net, dev_addr->bound_dev_if);