From d016071ca577e32ea9ebc0ed6fa39c8b22cb6788 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 1 Jun 2017 17:18:57 +0200 Subject: [PATCH] megasas: do not read iovec count more than once from frame Avoid TOC-TOU bugs depending on how the compiler behaves. Signed-off-by: Paolo Bonzini (cherry picked from commit 24c0c77af515acbf0f9705e8096f33ef24d37430) Signed-off-by: Michael Roth --- hw/scsi/megasas.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c index 1888118e5f..c353118882 100644 --- a/hw/scsi/megasas.c +++ b/hw/scsi/megasas.c @@ -675,15 +675,16 @@ out: static int megasas_map_dcmd(MegasasState *s, MegasasCmd *cmd) { dma_addr_t iov_pa, iov_size; + int iov_count; cmd->flags = le16_to_cpu(cmd->frame->header.flags); - if (!cmd->frame->header.sge_count) { + iov_count = cmd->frame->header.sge_count; + if (!iov_count) { trace_megasas_dcmd_zero_sge(cmd->index); cmd->iov_size = 0; return 0; - } else if (cmd->frame->header.sge_count > 1) { - trace_megasas_dcmd_invalid_sge(cmd->index, - cmd->frame->header.sge_count); + } else if (iov_count > 1) { + trace_megasas_dcmd_invalid_sge(cmd->index, iov_count); cmd->iov_size = 0; return -EINVAL; } -- 2.39.2