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Re: [Qemu-devel] [PATCH for-3.1] nvme: fix out-of-bounds access to the C
From: |
Li Qiang |
Subject: |
Re: [Qemu-devel] [PATCH for-3.1] nvme: fix out-of-bounds access to the CMB |
Date: |
Fri, 16 Nov 2018 18:38:39 +0800 |
Paolo Bonzini <address@hidden> 于2018年11月16日周五 下午5:31写道:
> Because the CMB BAR has a min_access_size of 2, if you read the last
> byte it will try to memcpy *2* bytes from n->cmbuf, causing an off-by-one
> error. This is CVE-2018-16847.
>
> Another way to fix this might be to register the CMB as a RAM memory
> region, which would also be more efficient. However, that might be a
> change for big-endian machines; I didn't think this through and I don't
> know how real hardware works. Add a basic testcase for the CMB in case
> somebody does this change later on.
>
> Cc: Keith Busch <address@hidden>
> Cc: address@hidden
> Cc: Li Qiang <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>
---
> hw/block/nvme.c | 2 +-
> tests/Makefile.include | 2 +-
> tests/nvme-test.c | 58 +++++++++++++++++++++++++++++++++++++++---
> 3 files changed, 57 insertions(+), 5 deletions(-)
>
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index 09d7c90259..5d92794ef7 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -1192,7 +1192,7 @@ static const MemoryRegionOps nvme_cmb_ops = {
> .write = nvme_cmb_write,
> .endianness = DEVICE_LITTLE_ENDIAN,
> .impl = {
> - .min_access_size = 2,
> + .min_access_size = 1,
> .max_access_size = 8,
> },
> };
> diff --git a/tests/Makefile.include b/tests/Makefile.include
> index 613242bc6e..fb0b449c02 100644
> --- a/tests/Makefile.include
> +++ b/tests/Makefile.include
> @@ -730,7 +730,7 @@ tests/test-hmp$(EXESUF): tests/test-hmp.o
> tests/machine-none-test$(EXESUF): tests/machine-none-test.o
> tests/drive_del-test$(EXESUF): tests/drive_del-test.o
> $(libqos-virtio-obj-y)
> tests/qdev-monitor-test$(EXESUF): tests/qdev-monitor-test.o
> $(libqos-pc-obj-y)
> -tests/nvme-test$(EXESUF): tests/nvme-test.o
> +tests/nvme-test$(EXESUF): tests/nvme-test.o $(libqos-pc-obj-y)
> tests/pvpanic-test$(EXESUF): tests/pvpanic-test.o
> tests/i82801b11-test$(EXESUF): tests/i82801b11-test.o
> tests/ac97-test$(EXESUF): tests/ac97-test.o
> diff --git a/tests/nvme-test.c b/tests/nvme-test.c
> index 7674a446e4..2abb3b6d19 100644
> --- a/tests/nvme-test.c
> +++ b/tests/nvme-test.c
> @@ -8,11 +8,64 @@
> */
>
> #include "qemu/osdep.h"
> +#include "qemu/units.h"
> #include "libqtest.h"
> +#include "libqos/libqos-pc.h"
> +
> +static QOSState *qnvme_start(const char *extra_opts)
> +{
> + QOSState *qs;
> + const char *arch = qtest_get_arch();
> + const char *cmd = "-drive id=drv0,if=none,file=null-co://,format=raw "
> + "-device nvme,addr=0x4.0,serial=foo,drive=drv0 %s";
> +
> + if (strcmp(arch, "i386") == 0 || strcmp(arch, "x86_64") == 0) {
> + qs = qtest_pc_boot(cmd, extra_opts ? : "");
> + global_qtest = qs->qts;
> + return qs;
> + }
> +
> + g_printerr("nvme tests are only available on x86\n");
> + exit(EXIT_FAILURE);
> +}
> +
> +static void qnvme_stop(QOSState *qs)
> +{
> + qtest_shutdown(qs);
> +}
>
> -/* Tests only initialization so far. TODO: Replace with functional tests
> */
> static void nop(void)
> {
> + QOSState *qs;
> +
> + qs = qnvme_start(NULL);
> + qnvme_stop(qs);
> +}
> +
> +static void nvmetest_cmb_test(void)
> +{
> + const int cmb_bar_size = 2 * MiB;
> + QOSState *qs;
> + QPCIDevice *pdev;
> + QPCIBar bar;
> +
> + qs = qnvme_start("-global nvme.cmb_size_mb=2");
> + pdev = qpci_device_find(qs->pcibus, QPCI_DEVFN(4,0));
> + g_assert(pdev != NULL);
> +
> + qpci_device_enable(pdev);
> + bar = qpci_iomap(pdev, 2, NULL);
> +
> + qpci_io_writel(pdev, bar, 0, 0xccbbaa99);
> + g_assert_cmpint(qpci_io_readb(pdev, bar, 0), ==, 0x99);
> + g_assert_cmpint(qpci_io_readw(pdev, bar, 0), ==, 0xaa99);
> +
> + /* Test partially out-of-bounds accesses. */
> + qpci_io_writel(pdev, bar, cmb_bar_size - 1, 0x44332211);
> + g_assert_cmpint(qpci_io_readb(pdev, bar, cmb_bar_size - 1), ==, 0x11);
> + g_assert_cmpint(qpci_io_readw(pdev, bar, cmb_bar_size - 1), !=,
> 0x2211);
> + g_assert_cmpint(qpci_io_readl(pdev, bar, cmb_bar_size - 1), !=,
> 0x44332211);
>
Here seems need a g_free(pdev),
> + qnvme_stop(qs);
> }
>
> int main(int argc, char **argv)
> @@ -21,9 +74,8 @@ int main(int argc, char **argv)
>
> g_test_init(&argc, &argv, NULL);
> qtest_add_func("/nvme/nop", nop);
> + qtest_add_func("/nvme/cmb_test", nvmetest_cmb_test);
>
> - qtest_start("-drive id=drv0,if=none,file=null-co://,format=raw "
> - "-device nvme,drive=drv0,serial=foo");
> ret = g_test_run();
>
> qtest_end();
>
There is no qtest_start(), this qtest_end() seems trigger an assert in glib.
(tests/nvme-test:44053): GLib-CRITICAL **: g_hook_destroy_link: assertion
'hook != NULL' failed
Otherwise
Reviewed-by: Li Qiang <address@hidden>
Tested-by: Li Qiang <address@hidden>
Thanks,
Li Qiang
> --
> 2.19.1
>
>