Re: [Qemu-devel] [PATCH 2/2] scsi: mptconfig: fix an assert expression

[Paolo Bonzini]

On 31/08/2016 14:06, P J P wrote:
> diff --git a/hw/scsi/mptconfig.c b/hw/scsi/mptconfig.c
> index 1ec895b..531947f 100644
> --- a/hw/scsi/mptconfig.c
> +++ b/hw/scsi/mptconfig.c
> @@ -158,7 +158,7 @@ static size_t mptsas_config_pack(uint8_t **data, const 
> char *fmt, ...)
>      va_end(ap);
>  
>      if (data) {
> -        assert(ret < 256 && (ret % 4) == 0);
> +        assert(ret / 4 < 256);
>          stb_p(*data + 1, ret / 4);
>      }
>      return ret;
> 

The (ret % 4) == 0 part is still useful.  Here is the patch I'm
committing with a commit message that explains the change:

commit f7a080e249008fdb90b070dff15d45690b6a06b8
Author: Prasad J Pandit <p...@fedoraproject.org>
Date:   Wed Aug 31 17:36:07 2016 +0530

    scsi: mptconfig: fix an assert expression
    
    When LSI SAS1068 Host Bus emulator builds configuration page
    headers, mptsas_config_pack() should assert that the size
    fits in a byte.  However, the size is expressed in 32-bit
    units, so up to 1020 bytes fit.  The assertion was only
    allowing replies up to 252 bytes, so fix it.
    
    Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
    Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
    Message-Id: <1472645167-30765-2-git-send-email-ppan...@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>

diff --git a/hw/scsi/mptconfig.c b/hw/scsi/mptconfig.c
index 7071854..3e4f400 100644
--- a/hw/scsi/mptconfig.c
+++ b/hw/scsi/mptconfig.c
@@ -158,7 +158,7 @@ static size_t mptsas_config_pack(uint8_t **data, const char 
*fmt, ...)
     va_end(ap);
 
     if (data) {
-        assert(ret < 256 && (ret % 4) == 0);
+        assert(ret / 4 < 256 && (ret % 4) == 0);
         stb_p(*data + 1, ret / 4);
     }
     return ret;