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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Thu, 19 May 2016 16:09:31 +0530
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Subject: [PATCH] esp: check dma length before reading scsi
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command(CVE-2016-4441)
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The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
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FIFO buffer. It is used to handle command and data transfer.
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Routine get_cmd() uses DMA to read scsi commands into this buffer.
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Add check to validate DMA length against buffer size to avoid any
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overrun.
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Fixes CVE-2016-4441.
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Reported-by: Li Qiang <liqiang6-s@360.cn>
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Message-Id: <1463654371-11169-3-git-send-email-ppandit@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 6c1fef6b59563cc415f21e03f81539ed4b33ad90)
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---
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hw/scsi/esp.c | 11 +++++++----
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1 file changed, 7 insertions(+), 4 deletions(-)
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diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
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index 01497e6..591c817 100644
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--- a/hw/scsi/esp.c
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+++ b/hw/scsi/esp.c
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@@ -82,7 +82,7 @@ void esp_request_cancelled(SCSIRequest *req)
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}
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}
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-static uint32_t get_cmd(ESPState *s, uint8_t *buf)
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+static uint32_t get_cmd(ESPState *s, uint8_t *buf, uint8_t buflen)
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{
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uint32_t dmalen;
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int target;
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@@ -92,6 +92,9 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf)
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dmalen = s->rregs[ESP_TCLO];
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dmalen |= s->rregs[ESP_TCMID] << 8;
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dmalen |= s->rregs[ESP_TCHI] << 16;
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+ if (dmalen > buflen) {
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+ return 0;
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+ }
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s->dma_memory_read(s->dma_opaque, buf, dmalen);
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} else {
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dmalen = s->ti_size;
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@@ -166,7 +169,7 @@ static void handle_satn(ESPState *s)
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s->dma_cb = handle_satn;
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return;
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}
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- len = get_cmd(s, buf);
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+ len = get_cmd(s, buf, sizeof(buf));
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if (len)
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do_cmd(s, buf);
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}
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@@ -180,7 +183,7 @@ static void handle_s_without_atn(ESPState *s)
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s->dma_cb = handle_s_without_atn;
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return;
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}
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- len = get_cmd(s, buf);
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+ len = get_cmd(s, buf, sizeof(buf));
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if (len) {
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do_busid_cmd(s, buf, 0);
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}
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@@ -192,7 +195,7 @@ static void handle_satn_stop(ESPState *s)
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s->dma_cb = handle_satn_stop;
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return;
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}
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- s->cmdlen = get_cmd(s, s->cmdbuf);
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+ s->cmdlen = get_cmd(s, s->cmdbuf, sizeof(s->cmdbuf));
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if (s->cmdlen) {
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trace_esp_handle_satn_stop(s->cmdlen);
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s->do_cmd = 1;
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