From fd72da696d48452bf9ffc4816e049f4ed18f6117 Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Wed, 7 Nov 2018 18:00:06 +0100

Subject: [PATCH 32/34] scsi-generic: avoid invalid access to struct when

 emulating block limits

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RH-Author: Paolo Bonzini <pbonzini@redhat.com>

Message-id: <20181107180007.22954-9-pbonzini@redhat.com>

Patchwork-id: 82946

O-Subject: [RHEL7.6.z qemu-kvm-rhev PATCH 8/9] scsi-generic: avoid invalid access to struct when emulating block limits

Bugzilla: 1566195

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Emulation of the block limits VPD page called back into scsi-disk.c,

which however expected the request to be for a SCSIDiskState and

accessed a scsi-generic device outside the bounds of its struct

(namely to retrieve s->max_unmap_size and s->max_io_size).

To avoid this, move the emulation code to a separate function that

takes a new SCSIBlockLimits struct and marshals it into the VPD

response format.

Reported-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit 3d4a8bf0eed68a781e06118e4d1df6e2f106a1f2)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/scsi/Makefile.objs       |  2 +-

 hw/scsi/emulation.c         | 42 +++++++++++++++++++++

 hw/scsi/scsi-disk.c         | 92 ++++++++++-----------------------------------

 hw/scsi/scsi-generic.c      | 35 ++++++++++++-----

 include/hw/scsi/emulation.h | 16 ++++++++

 include/hw/scsi/scsi.h      |  1 -

 6 files changed, 104 insertions(+), 84 deletions(-)

 create mode 100644 hw/scsi/emulation.c

 create mode 100644 include/hw/scsi/emulation.h

diff --git a/hw/scsi/Makefile.objs b/hw/scsi/Makefile.objs

index b188f72..c4f249a 100644

--- a/hw/scsi/Makefile.objs

+++ b/hw/scsi/Makefile.objs

@@ -1,4 +1,4 @@

-common-obj-y += scsi-disk.o

+common-obj-y += scsi-disk.o emulation.o

 common-obj-y += scsi-generic.o scsi-bus.o

 common-obj-$(CONFIG_LSI_SCSI_PCI) += lsi53c895a.o

 common-obj-$(CONFIG_MPTSAS_SCSI_PCI) += mptsas.o mptconfig.o mptendian.o

diff --git a/hw/scsi/emulation.c b/hw/scsi/emulation.c

new file mode 100644

index 0000000..06d62f3

--- /dev/null

+++ b/hw/scsi/emulation.c

@@ -0,0 +1,42 @@

+#include "qemu/osdep.h"

+#include "qemu/units.h"

+#include "qemu/bswap.h"

+#include "hw/scsi/emulation.h"

+

+int scsi_emulate_block_limits(uint8_t *outbuf, const SCSIBlockLimits *bl)

+{

+    /* required VPD size with unmap support */

+    memset(outbuf, 0, 0x3c);

+

+    outbuf[0] = bl->wsnz; /* wsnz */

+

+    if (bl->max_io_sectors) {

+        /* optimal transfer length granularity.  This field and the optimal

+         * transfer length can't be greater than maximum transfer length.

+         */

+        stw_be_p(outbuf + 2, MIN(bl->min_io_size, bl->max_io_sectors));

+

+        /* maximum transfer length */

+        stl_be_p(outbuf + 4, bl->max_io_sectors);

+

+        /* optimal transfer length */

+        stl_be_p(outbuf + 8, MIN(bl->opt_io_size, bl->max_io_sectors));

+    } else {

+        stw_be_p(outbuf + 2, bl->min_io_size);

+        stl_be_p(outbuf + 8, bl->opt_io_size);

+    }

+

+    /* max unmap LBA count */

+    stl_be_p(outbuf + 16, bl->max_unmap_sectors);

+

+    /* max unmap descriptors */

+    stl_be_p(outbuf + 20, bl->max_unmap_descr);

+

+    /* optimal unmap granularity; alignment is zero */

+    stl_be_p(outbuf + 24, bl->unmap_sectors);

+

+    /* max write same size, make it the same as maximum transfer length */

+    stl_be_p(outbuf + 36, bl->max_io_sectors);

+

+    return 0x3c;

+}

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c

index b8a27d6..a20ef91 100644

--- a/hw/scsi/scsi-disk.c

+++ b/hw/scsi/scsi-disk.c

@@ -32,6 +32,7 @@ do { printf("scsi-disk: " fmt , ## __VA_ARGS__); } while (0)

 #include "qapi/error.h"

 #include "qemu/error-report.h"

 #include "hw/scsi/scsi.h"

+#include "hw/scsi/emulation.h"

 #include "scsi/constants.h"

 #include "sysemu/sysemu.h"

 #include "sysemu/block-backend.h"

@@ -585,7 +586,7 @@ static uint8_t *scsi_get_buf(SCSIRequest *req)

     return (uint8_t *)r->iov.iov_base;

 }

-int scsi_disk_emulate_vpd_page(SCSIRequest *req, uint8_t *outbuf)

+static int scsi_disk_emulate_vpd_page(SCSIRequest *req, uint8_t *outbuf)

 {

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

     uint8_t page_code = req->cmd.buf[2];

@@ -687,89 +688,36 @@ int scsi_disk_emulate_vpd_page(SCSIRequest *req, uint8_t *outbuf)

     }

     case 0xb0: /* block limits */

     {

-        unsigned int unmap_sectors =

-            s->qdev.conf.discard_granularity / s->qdev.blocksize;

-        unsigned int min_io_size =

-            s->qdev.conf.min_io_size / s->qdev.blocksize;

-        unsigned int opt_io_size =

-            s->qdev.conf.opt_io_size / s->qdev.blocksize;

-        unsigned int max_unmap_sectors =

-            s->max_unmap_size / s->qdev.blocksize;

-        unsigned int max_io_sectors =

-            s->max_io_size / s->qdev.blocksize;

+        SCSIBlockLimits bl = {};

         if (s->qdev.type == TYPE_ROM) {

             DPRINTF("Inquiry (EVPD[%02X] not supported for CDROM\n",

                     page_code);

             return -1;

         }

+        bl.wsnz = 1;

+        bl.unmap_sectors =

+            s->qdev.conf.discard_granularity / s->qdev.blocksize;

+        bl.min_io_size =

+            s->qdev.conf.min_io_size / s->qdev.blocksize;

+        bl.opt_io_size =

+            s->qdev.conf.opt_io_size / s->qdev.blocksize;

+        bl.max_unmap_sectors =

+            s->max_unmap_size / s->qdev.blocksize;

+        bl.max_io_sectors =

+            s->max_io_size / s->qdev.blocksize;

+        /* 255 descriptors fit in 4 KiB with an 8-byte header */

+        bl.max_unmap_descr = 255;

+

         if (s->qdev.type == TYPE_DISK) {

             int max_transfer_blk = blk_get_max_transfer(s->qdev.conf.blk);

             int max_io_sectors_blk =

                 max_transfer_blk / s->qdev.blocksize;

-            max_io_sectors =

-                MIN_NON_ZERO(max_io_sectors_blk, max_io_sectors);

-

-            /* min_io_size and opt_io_size can't be greater than

-             * max_io_sectors */

-            if (min_io_size) {

-                min_io_size = MIN(min_io_size, max_io_sectors);

-            }

-            if (opt_io_size) {

-                opt_io_size = MIN(opt_io_size, max_io_sectors);

-            }

+            bl.max_io_sectors =

+                MIN_NON_ZERO(max_io_sectors_blk, bl.max_io_sectors);

         }

-        /* required VPD size with unmap support */

-        buflen = 0x40;

-        memset(outbuf + 4, 0, buflen - 4);

-

-        outbuf[4] = 0x1; /* wsnz */

-

-        /* optimal transfer length granularity */

-        outbuf[6] = (min_io_size >> 8) & 0xff;

-        outbuf[7] = min_io_size & 0xff;

-

-        /* maximum transfer length */

-        outbuf[8] = (max_io_sectors >> 24) & 0xff;

-        outbuf[9] = (max_io_sectors >> 16) & 0xff;

-        outbuf[10] = (max_io_sectors >> 8) & 0xff;

-        outbuf[11] = max_io_sectors & 0xff;

-

-        /* optimal transfer length */

-        outbuf[12] = (opt_io_size >> 24) & 0xff;

-        outbuf[13] = (opt_io_size >> 16) & 0xff;

-        outbuf[14] = (opt_io_size >> 8) & 0xff;

-        outbuf[15] = opt_io_size & 0xff;

-

-        /* max unmap LBA count, default is 1GB */

-        outbuf[20] = (max_unmap_sectors >> 24) & 0xff;

-        outbuf[21] = (max_unmap_sectors >> 16) & 0xff;

-        outbuf[22] = (max_unmap_sectors >> 8) & 0xff;

-        outbuf[23] = max_unmap_sectors & 0xff;

-

-        /* max unmap descriptors, 255 fit in 4 kb with an 8-byte header */

-        outbuf[24] = 0;

-        outbuf[25] = 0;

-        outbuf[26] = 0;

-        outbuf[27] = 255;

-

-        /* optimal unmap granularity */

-        outbuf[28] = (unmap_sectors >> 24) & 0xff;

-        outbuf[29] = (unmap_sectors >> 16) & 0xff;

-        outbuf[30] = (unmap_sectors >> 8) & 0xff;

-        outbuf[31] = unmap_sectors & 0xff;

-

-        /* max write same size */

-        outbuf[36] = 0;

-        outbuf[37] = 0;

-        outbuf[38] = 0;

-        outbuf[39] = 0;

-

-        outbuf[40] = (max_io_sectors >> 24) & 0xff;

-        outbuf[41] = (max_io_sectors >> 16) & 0xff;

-        outbuf[42] = (max_io_sectors >> 8) & 0xff;

-        outbuf[43] = max_io_sectors & 0xff;

+        buflen += scsi_emulate_block_limits(outbuf + buflen, &bl);

         break;

     }

     case 0xb1: /* block device characteristics */

diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c

index 6d6db69..f218cef 100644

--- a/hw/scsi/scsi-generic.c

+++ b/hw/scsi/scsi-generic.c

@@ -16,6 +16,7 @@

 #include "qemu-common.h"

 #include "qemu/error-report.h"

 #include "hw/scsi/scsi.h"

+#include "hw/scsi/emulation.h"

 #include "sysemu/block-backend.h"

 #include "sysemu/blockdev.h"

@@ -182,7 +183,7 @@ static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)

             /* Also take care of the opt xfer len. */

             stl_be_p(&r->buf[12],

                     MIN_NON_ZERO(max_transfer, ldl_be_p(&r->buf[12])));

-        } else if (page == 0x00 && s->needs_vpd_bl_emulation) {

+        } else if (s->needs_vpd_bl_emulation && page == 0x00) {

             /*

              * Now we're capable of supplying the VPD Block Limits

              * response if the hardware can't. Add it in the INQUIRY

@@ -210,9 +211,24 @@ static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)

     }

 }

-static int scsi_emulate_block_limits(SCSIGenericReq *r)

+static int scsi_generic_emulate_block_limits(SCSIGenericReq *r, SCSIDevice *s)

 {

-    r->buflen = scsi_disk_emulate_vpd_page(&r->req, r->buf);

+    int len;

+    uint8_t buf[64];

+

+    SCSIBlockLimits bl = {

+        .max_io_sectors = blk_get_max_transfer(s->conf.blk) / s->blocksize

+    };

+

+    memset(r->buf, 0, r->buflen);

+    stb_p(buf, s->type);

+    stb_p(buf + 1, 0xb0);

+    len = scsi_emulate_block_limits(buf + 4, &bl);

+    assert(len <= sizeof(buf) - 4);

+    stw_be_p(buf + 2, len);

+

+    memcpy(r->buf, buf, MIN(r->buflen, len + 4));

+

     r->io_header.sb_len_wr = 0;

     /*

@@ -254,13 +270,12 @@ static void scsi_read_complete(void * opaque, int ret)

      * resulted in sense error but would need emulation.

      * In this case, emulate a valid VPD response.

      */

-    if (s->needs_vpd_bl_emulation) {

-        int is_vpd_bl = r->req.cmd.buf[0] == INQUIRY &&

-                         r->req.cmd.buf[1] & 0x01 &&

-                         r->req.cmd.buf[2] == 0xb0;

-

-        if (is_vpd_bl && sg_io_sense_from_errno(-ret, &r->io_header, &sense)) {

-            len = scsi_emulate_block_limits(r);

+    if (s->needs_vpd_bl_emulation &&

+        r->req.cmd.buf[0] == INQUIRY &&

+        (r->req.cmd.buf[1] & 0x01) &&

+        r->req.cmd.buf[2] == 0xb0) {

+        if (sg_io_sense_from_errno(-ret, &r->io_header, &sense)) {

+            len = scsi_generic_emulate_block_limits(r, s);

             /*

              * No need to let scsi_read_complete go on and handle an

              * INQUIRY VPD BL request we created manually.

diff --git a/include/hw/scsi/emulation.h b/include/hw/scsi/emulation.h

new file mode 100644

index 0000000..09fba1f

--- /dev/null

+++ b/include/hw/scsi/emulation.h

@@ -0,0 +1,16 @@

+#ifndef HW_SCSI_EMULATION_H

+#define HW_SCSI_EMULATION_H 1

+

+typedef struct SCSIBlockLimits {

+    bool wsnz;

+    uint16_t min_io_size;

+    uint32_t max_unmap_descr;

+    uint32_t opt_io_size;

+    uint32_t max_unmap_sectors;

+    uint32_t unmap_sectors;

+    uint32_t max_io_sectors;

+} SCSIBlockLimits;

+

+int scsi_emulate_block_limits(uint8_t *outbuf, const SCSIBlockLimits *bl);

+

+#endif

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h

index ee3a411..acef25f 100644

--- a/include/hw/scsi/scsi.h

+++ b/include/hw/scsi/scsi.h

@@ -189,7 +189,6 @@ void scsi_device_report_change(SCSIDevice *dev, SCSISense sense);

 void scsi_device_unit_attention_reported(SCSIDevice *dev);

 void scsi_generic_read_device_inquiry(SCSIDevice *dev);

 int scsi_device_get_sense(SCSIDevice *dev, uint8_t *buf, int len, bool fixed);

-int scsi_disk_emulate_vpd_page(SCSIRequest *req, uint8_t *outbuf);

 int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,

                         uint8_t *buf, uint8_t buf_size);

 SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int target, int lun);

-- 

1.8.3.1