[Qemu-devel] [PATCH] scsi: fix scsi_convert_sense crash when in_buf == NULL && in_len == 0

[Qemu-devel] [PATCH] scsi: fix scsi_convert_sense crash when in_buf == NULL && in_len == 0

[Paolo Bonzini]

scsi_disk_emulate_command passes in_buf == NULL when sent a REQUEST
SENSE command.  Check for in_len == 0 before dereferencing in_buf.

Fixes: f68d98b21fa74155dc7c1fd212474379ac3c7531
Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 scsi/utils.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/scsi/utils.c b/scsi/utils.c
index ddae650a99..8738522955 100644
--- a/scsi/utils.c
+++ b/scsi/utils.c
@@ -322,18 +322,18 @@ int scsi_convert_sense(uint8_t *in_buf, int in_len,
     SCSISense sense;
     bool fixed_in;
 
+    if (in_len == 0) {
+        return scsi_build_sense_buf(buf, len, SENSE_CODE(NO_SENSE), fixed);
+    }
+
     fixed_in = (in_buf[0] & 2) == 0;
-    if (in_len && fixed == fixed_in) {
+    if (fixed == fixed_in) {
         memcpy(buf, in_buf, MIN(len, in_len));
         return MIN(len, in_len);
-    }
-
-    if (in_len == 0) {
-        sense = SENSE_CODE(NO_SENSE);
     } else {
         sense = scsi_parse_sense_buf(in_buf, in_len);
+        return scsi_build_sense_buf(buf, len, sense, fixed);
     }
-    return scsi_build_sense_buf(buf, len, sense, fixed);
 }
 
 int scsi_sense_to_errno(int key, int asc, int ascq)
-- 
2.14.3

Re: [Qemu-devel] [PATCH] scsi: fix scsi_convert_sense crash when in_buf == NULL && in_len == 0

[Roman Kagan]

On Fri, Dec 22, 2017 at 04:55:22PM +0100, Paolo Bonzini wrote:
> scsi_disk_emulate_command passes in_buf == NULL when sent a REQUEST
> SENSE command.  Check for in_len == 0 before dereferencing in_buf.
> 
> Fixes: f68d98b21fa74155dc7c1fd212474379ac3c7531
> Reported-by: Roman Kagan <rkagan@virtuozzo.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  scsi/utils.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

Tested-by: Roman Kagan <rkagan@virtuozzo.com>

Re: [Qemu-devel] [PATCH] scsi: fix scsi_convert_sense crash when in_buf == NULL && in_len == 0

[Eric Blake]

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On 12/22/2017 09:55 AM, Paolo Bonzini wrote:
> scsi_disk_emulate_command passes in_buf == NULL when sent a REQUEST
> SENSE command.  Check for in_len == 0 before dereferencing in_buf.
> 
> Fixes: f68d98b21fa74155dc7c1fd212474379ac3c7531
> Reported-by: Roman Kagan <rkagan@virtuozzo.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  scsi/utils.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

How does this compare to
https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg00582.html ?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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