xlnx_dp_read allows an out-of-bounds read at its default branch because of an improper index.
According to https://www.xilinx.com/html_docs/registers/ug1087/ug1087-zynq-ultrascale-registers.html (DP Module), registers 0x3A4/0x3A4/0x3AC are allowed. DP_INT_MASK 0x000003A4 32 mixed 0xFFFFF03F Interrupt Mask Register for intrN. DP_INT_EN 0x000003A8 32 mixed 0x00000000 Interrupt Enable Register. DP_INT_DS 0x000003AC 32 mixed 0x00000000 Interrupt Disable Register. In xlnx_dp_write, when the offset is 0x3A8 and 0x3AC, the virtual device will write s->core_registers[0x3A4 >> 2]. That is to say, the maxize of s->core_registers could be ((0x3A4 >> 2) + 1). However, the current size of s->core_registers is (0x3AF >> >> 2), that is ((0x3A4 >> 2) + 2), which is out of the range. In xlxn_dp_read, the access to offset 0x3A8 or 0x3AC will be directed to the offset 0x3A8 (incorrect functionality) or 0x3AC (out-of-bounds read) rather than 0x3A4. This patch adjusts the size of s->core_registers and enforces the read access to offset 0x3A* and 0x3AC to 0x3A4. BTW, because the size of this MMIO region is 0x3AF, this patch also removes the assertion in xlnx_dp_write. Fixes: 58ac482a66de ("introduce xlnx-dp") Signed-off-by: Qiang Liu <cyruscy...@gmail.com> --- hw/display/xlnx_dp.c | 7 ++++--- include/hw/display/xlnx_dp.h | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c index 7bcbb13..8903181 100644 --- a/hw/display/xlnx_dp.c +++ b/hw/display/xlnx_dp.c @@ -713,8 +713,10 @@ static uint64_t xlnx_dp_read(void *opaque, hwaddr offset, unsigned size) ret = 0; break; default: - assert(offset <= (0x3AC >> 2)); - ret = s->core_registers[offset]; + if (offset == (0x3A8 >> 2) || offset == (0x3AC >> 2)) + ret = s->core_registers[DP_INT_MASK]; + else + ret = s->core_registers[offset]; break; } @@ -876,7 +878,6 @@ static void xlnx_dp_write(void *opaque, hwaddr offset, uint64_t value, xlnx_dp_update_irq(s); break; default: - assert(offset <= (0x504C >> 2)); s->core_registers[offset] = value; break; } diff --git a/include/hw/display/xlnx_dp.h b/include/hw/display/xlnx_dp.h index e85e428..99a6d47 100644 --- a/include/hw/display/xlnx_dp.h +++ b/include/hw/display/xlnx_dp.h @@ -39,7 +39,7 @@ #define AUD_CHBUF_MAX_DEPTH (32 * KiB) #define MAX_QEMU_BUFFER_SIZE (4 * KiB) -#define DP_CORE_REG_ARRAY_SIZE (0x3AF >> 2) +#define DP_CORE_REG_ARRAY_SIZE (0x3A8 >> 2) #define DP_AVBUF_REG_ARRAY_SIZE (0x238 >> 2) #define DP_VBLEND_REG_ARRAY_SIZE (0x1DF >> 2) #define DP_AUDIO_REG_ARRAY_SIZE (0x50 >> 2) -- 2.7.4
