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nvme: fix out-of-bounds access to the CMB 

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 <keith.busch@intel.com>
Cc: qemu-block@nongnu.org
Reported-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Tested-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 87ad860c62)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
stable-3.0
Paolo Bonzini 2018-11-20 19:41:48 +01:00 committed by Michael Roth
parent 2c4f6cabf5
commit e49f868dc0
3 changed files with 60 additions and 12 deletions
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2
hw/block/nvme.c
View File

@ -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,
},
};

2
tests/Makefile.include
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@ -821,7 +821,7 @@ 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

68
tests/nvme-test.c
View File

@ -8,25 +8,73 @@
*/
#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);
g_free(pdev);
qnvme_stop(qs);
}
int main(int argc, char **argv)
{
int ret;
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();
return ret;
return g_test_run();
}