The patch below does not apply to the 4.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 308aa2b8f7b7db3332a7d41099fd37851fb793b2 Mon Sep 17 00:00:00 2001

From: Steve Wise swise@opengridcomputing.com Date: Fri, 31 Aug 2018 07:15:56 -0700 Subject: [PATCH] iw_cxgb4: only allow 1 flush on user qps

Once the qp has been flushed, it cannot be flushed again. The user qp flush logic wasn't enforcing it however. The bug can cause touch-after-free crashes like:

Unable to handle kernel paging request for data at address 0x000001ec Faulting instruction address: 0xc008000016069100 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [c008000016069100] flush_qp+0x80/0x480 [iw_cxgb4] LR [c00800001606cd6c] c4iw_modify_qp+0x71c/0x11d0 [iw_cxgb4] Call Trace: [c00800001606cd6c] c4iw_modify_qp+0x71c/0x11d0 [iw_cxgb4] [c00800001606e868] c4iw_ib_modify_qp+0x118/0x200 [iw_cxgb4] [c0080000119eae80] ib_security_modify_qp+0xd0/0x3d0 [ib_core] [c0080000119c4e24] ib_modify_qp+0xc4/0x2c0 [ib_core] [c008000011df0284] iwcm_modify_qp_err+0x44/0x70 [iw_cm] [c008000011df0fec] destroy_cm_id+0xcc/0x370 [iw_cm] [c008000011ed4358] rdma_destroy_id+0x3c8/0x520 [rdma_cm] [c0080000134b0540] ucma_close+0x90/0x1b0 [rdma_ucm] [c000000000444da4] __fput+0xe4/0x2f0

So fix flush_qp() to only flush the wq once.

Cc: stable@vger.kernel.org Signed-off-by: Steve Wise swise@opengridcomputing.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com

diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c index b3203afa3b1d..347fe18b1a41 100644 --- a/drivers/infiniband/hw/cxgb4/qp.c +++ b/drivers/infiniband/hw/cxgb4/qp.c @@ -1685,6 +1685,12 @@ static void flush_qp(struct c4iw_qp *qhp) schp = to_c4iw_cq(qhp->ibqp.send_cq);

if (qhp->ibqp.uobject) { + + /* for user qps, qhp->wq.flushed is protected by qhp->mutex */ + if (qhp->wq.flushed) + return; + + qhp->wq.flushed = 1; t4_set_wq_in_error(&qhp->wq, 0); t4_set_cq_in_error(&rchp->cq); spin_lock_irqsave(&rchp->comp_handler_lock, flag);