qemu-kvm/kvm-hw-ide-reset-cancel-async-DMA-operation-before-reset.patch

From 2308abf0c5da2fe35a0721318c31d22e077663c2 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Fri, 24 Nov 2023 12:17:11 -0500
Subject: [PATCH 1/2] hw/ide: reset: cancel async DMA operation before
 resetting state
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 335: hw/ide: reset: cancel async DMA operation before resetting state
RH-Jira: RHEL-15437
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Commit: [1/2] b0f5f7f888559a210f1c6b3c545e337dbbc9cf22 (redhat/rhel/src/qemu-kvm/jons-qemu-kvm-2)

JIRA: https://issues.redhat.com/browse/RHEL-15437
CVE: CVE-2023-5088
Upstream: Merged

commit 7d7512019fc40c577e2bdd61f114f31a9eb84a8e
Author: Fiona Ebner <f.ebner@proxmox.com>
Date:   Wed Sep 6 15:09:21 2023 +0200

    hw/ide: reset: cancel async DMA operation before resetting state

    If there is a pending DMA operation during ide_bus_reset(), the fact
    that the IDEState is already reset before the operation is canceled
    can be problematic. In particular, ide_dma_cb() might be called and
    then use the reset IDEState which contains the signature after the
    reset. When used to construct the IO operation this leads to
    ide_get_sector() returning 0 and nsector being 1. This is particularly
    bad, because a write command will thus destroy the first sector which
    often contains a partition table or similar.

    Traces showing the unsolicited write happening with IDEState
    0x5595af6949d0 being used after reset:

    > ahci_port_write ahci(0x5595af6923f0)[0]: port write [reg:PxSCTL] @ 0x2c: 0x00000300
    > ahci_reset_port ahci(0x5595af6923f0)[0]: reset port
    > ide_reset IDEstate 0x5595af6949d0
    > ide_reset IDEstate 0x5595af694da8
    > ide_bus_reset_aio aio_cancel
    > dma_aio_cancel dbs=0x7f64600089a0
    > dma_blk_cb dbs=0x7f64600089a0 ret=0
    > dma_complete dbs=0x7f64600089a0 ret=0 cb=0x5595acd40b30
    > ahci_populate_sglist ahci(0x5595af6923f0)[0]
    > ahci_dma_prepare_buf ahci(0x5595af6923f0)[0]: prepare buf limit=512 prepared=512
    > ide_dma_cb IDEState 0x5595af6949d0; sector_num=0 n=1 cmd=DMA WRITE
    > dma_blk_io dbs=0x7f6420802010 bs=0x5595ae2c6c30 offset=0 to_dev=1
    > dma_blk_cb dbs=0x7f6420802010 ret=0

    > (gdb) p *qiov
    > $11 = {iov = 0x7f647c76d840, niov = 1, {{nalloc = 1, local_iov = {iov_base = 0x0,
    >       iov_len = 512}}, {__pad = "\001\000\000\000\000\000\000\000\000\000\000",
    >       size = 512}}}
    > (gdb) bt
    > #0  blk_aio_pwritev (blk=0x5595ae2c6c30, offset=0, qiov=0x7f6420802070, flags=0,
    >     cb=0x5595ace6f0b0 <dma_blk_cb>, opaque=0x7f6420802010)
    >     at ../block/block-backend.c:1682
    > #1  0x00005595ace6f185 in dma_blk_cb (opaque=0x7f6420802010, ret=<optimized out>)
    >     at ../softmmu/dma-helpers.c:179
    > #2  0x00005595ace6f778 in dma_blk_io (ctx=0x5595ae0609f0,
    >     sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
    >     io_func=io_func@entry=0x5595ace6ee30 <dma_blk_write_io_func>,
    >     io_func_opaque=io_func_opaque@entry=0x5595ae2c6c30,
    >     cb=0x5595acd40b30 <ide_dma_cb>, opaque=0x5595af6949d0,
    >     dir=DMA_DIRECTION_TO_DEVICE) at ../softmmu/dma-helpers.c:244
    > #3  0x00005595ace6f90a in dma_blk_write (blk=0x5595ae2c6c30,
    >     sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
    >     cb=cb@entry=0x5595acd40b30 <ide_dma_cb>, opaque=opaque@entry=0x5595af6949d0)
    >     at ../softmmu/dma-helpers.c:280
    > #4  0x00005595acd40e18 in ide_dma_cb (opaque=0x5595af6949d0, ret=<optimized out>)
    >     at ../hw/ide/core.c:953
    > #5  0x00005595ace6f319 in dma_complete (ret=0, dbs=0x7f64600089a0)
    >     at ../softmmu/dma-helpers.c:107
    > #6  dma_blk_cb (opaque=0x7f64600089a0, ret=0) at ../softmmu/dma-helpers.c:127
    > #7  0x00005595ad12227d in blk_aio_complete (acb=0x7f6460005b10)
    >     at ../block/block-backend.c:1527
    > #8  blk_aio_complete (acb=0x7f6460005b10) at ../block/block-backend.c:1524
    > #9  blk_aio_write_entry (opaque=0x7f6460005b10) at ../block/block-backend.c:1594
    > #10 0x00005595ad258cfb in coroutine_trampoline (i0=<optimized out>,
    >     i1=<optimized out>) at ../util/coroutine-ucontext.c:177

    Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
    Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
    Tested-by: simon.rowe@nutanix.com
    Message-ID: <20230906130922.142845-1-f.ebner@proxmox.com>

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 hw/ide/core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 05a32d0a99..fd50c123e8 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2456,19 +2456,19 @@ static void ide_dummy_transfer_stop(IDEState *s)
 
 void ide_bus_reset(IDEBus *bus)
 {
-    bus->unit = 0;
-    bus->cmd = 0;
-    ide_reset(&bus->ifs[0]);
-    ide_reset(&bus->ifs[1]);
-    ide_clear_hob(bus);
-
-    /* pending async DMA */
+    /* pending async DMA - needs the IDEState before it is reset */
     if (bus->dma->aiocb) {
         trace_ide_bus_reset_aio();
         blk_aio_cancel(bus->dma->aiocb);
         bus->dma->aiocb = NULL;
     }
 
+    bus->unit = 0;
+    bus->cmd = 0;
+    ide_reset(&bus->ifs[0]);
+    ide_reset(&bus->ifs[1]);
+    ide_clear_hob(bus);
+
     /* reset dma provider too */
     if (bus->dma->ops->reset) {
         bus->dma->ops->reset(bus->dma);
-- 
2.41.0