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From 6c1fef6b59563cc415f21e03f81539ed4b33ad90 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 19 May 2016 16:09:31 +0530
Subject: [PATCH] esp: check dma length before reading scsi command(CVE-2016-4441)
The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
FIFO buffer. It is used to handle command and data transfer.
Routine get_cmd() uses DMA to read scsi commands into this buffer.
Add check to validate DMA length against buffer size to avoid any
overrun.
Fixes CVE-2016-4441.
Upstream-Status: Backport
Reported-by: Li Qiang <liqiang6-s@360.cn>
Cc: qemu-stable@nongnu.org
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1463654371-11169-3-git-send-email-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Adrian Dudau <adrian.dudau@enea.com>
---
hw/scsi/esp.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 01497e6..591c817 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -82,7 +82,7 @@ void esp_request_cancelled(SCSIRequest *req)
}
}
-static uint32_t get_cmd(ESPState *s, uint8_t *buf)
+static uint32_t get_cmd(ESPState *s, uint8_t *buf, uint8_t buflen)
{
uint32_t dmalen;
int target;
@@ -92,6 +92,9 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf)
dmalen = s->rregs[ESP_TCLO];
dmalen |= s->rregs[ESP_TCMID] << 8;
dmalen |= s->rregs[ESP_TCHI] << 16;
+ if (dmalen > buflen) {
+ return 0;
+ }
s->dma_memory_read(s->dma_opaque, buf, dmalen);
} else {
dmalen = s->ti_size;
@@ -166,7 +169,7 @@ static void handle_satn(ESPState *s)
s->dma_cb = handle_satn;
return;
}
- len = get_cmd(s, buf);
+ len = get_cmd(s, buf, sizeof(buf));
if (len)
do_cmd(s, buf);
}
@@ -180,7 +183,7 @@ static void handle_s_without_atn(ESPState *s)
s->dma_cb = handle_s_without_atn;
return;
}
- len = get_cmd(s, buf);
+ len = get_cmd(s, buf, sizeof(buf));
if (len) {
do_busid_cmd(s, buf, 0);
}
@@ -192,7 +195,7 @@ static void handle_satn_stop(ESPState *s)
s->dma_cb = handle_satn_stop;
return;
}
- s->cmdlen = get_cmd(s, s->cmdbuf);
+ s->cmdlen = get_cmd(s, s->cmdbuf, sizeof(s->cmdbuf));
if (s->cmdlen) {
trace_esp_handle_satn_stop(s->cmdlen);
s->do_cmd = 1;
--
1.7.0.4
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