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From: gerben@altlinux.org
To: richard.henderson@linaro.org, fred.konrad@greensocs.com,
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Cc: sdl.qemu@linuxtesting.org, Denis Rastyogin <gerben@altlinux.org>,
 David Meliksetyan <d.meliksetyan@fobos-nt.ru>
Subject: [PATCH v2] hw/display: refine upper limit for offset value in assert
 check
Date: Thu, 12 Dec 2024 19:01:54 +0300
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From: Denis Rastyogin <gerben@altlinux.org>

Accessing an element of the s->core_registers array,
which has a size of 236 (0x3AC), may lead to a buffer overflow
if the 'offset' index exceeds the valid range, potentially
reaching values up to 5139 (0x504C >> 2). Therefore, the bounds
check has been extended to DP_CORE_REG_ARRAY_SIZE (0x3B0 >> 2).
This change addresses a potential vulnerability by ensuring
the offset stays within the valid range before writing data.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Reported-by: David Meliksetyan <d.meliksetyan@fobos-nt.ru>
Signed-off-by: Denis Rastyogin <gerben@altlinux.org>
---
 hw/display/xlnx_dp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
index 6ab2335499..3f1f5d81bd 100644
--- a/hw/display/xlnx_dp.c
+++ b/hw/display/xlnx_dp.c
@@ -896,7 +896,11 @@ static void xlnx_dp_write(void *opaque, hwaddr offset,=
 uint64_t value,
         xlnx_dp_update_irq(s);
         break;
     default:
-        assert(offset <=3D (0x504C >> 2));
+        /*
+         * Check to ensure the offset is within the bounds of
+         * the core_registers[] array.
+        */
+        assert(offset < DP_CORE_REG_ARRAY_SIZE);
         s->core_registers[offset] =3D value;
         break;
     }
--=20
2.42.2