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