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Date: Fri, 28 Apr 2017 14:05:01 +0530 (IST)
From: P J P <ppandit@redhat.com>
In-Reply-To: <20170424120634.12268-1-ppandit@redhat.com>
Message-ID: <alpine.LFD.2.20.1704281403310.29240@wniryva>
References: <20170424120634.12268-1-ppandit@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] scsi: avoid an off-by-one error in
 megasas_mmio_write
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To: Qemu Developers <qemu-devel@nongnu.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, YY Z <bigbird475958471@gmail.com>

+-- On Mon, 24 Apr 2017, P J P wrote --+
| While reading magic sequence(MFI_SEQ) in megasas_mmio_write,
| an off-by-one error could occur as 's->adp_reset' index is not
| reset after reading the last sequence.
| 
| --- a/hw/scsi/megasas.c
| +++ b/hw/scsi/megasas.c
| @@ -2138,15 +2138,15 @@ static void megasas_mmio_write(void *opaque, hwaddr addr,
|      case MFI_SEQ:
|          trace_megasas_mmio_writel("MFI_SEQ", val);
|          /* Magic sequence to start ADP reset */
| -        if (adp_reset_seq[s->adp_reset] == val) {
| -            s->adp_reset++;
| +        if (adp_reset_seq[s->adp_reset++] == val) {
| +            if (s->adp_reset == 6) {
| +                s->adp_reset = 0;
| +                s->diag = MFI_DIAG_WRITE_ENABLE;
| +            }
|          } else {
|              s->adp_reset = 0;
|              s->diag = 0;
|          }
| -        if (s->adp_reset == 6) {
| -            s->diag = MFI_DIAG_WRITE_ENABLE;
| -        }
|          break;

Ping...!
--
Prasad J Pandit / Red Hat Product Security Team
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