From 0ffe88e6919d210c806078aaf0c34911554f1438 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Sat, 22 Jan 2022 18:24:41 +0000 Subject: [PATCH] hw/intc/arm_gicv3_its: Make GITS_BASER RAZ/WI for unimplemented registers The ITS has a bank of 8 GITS_BASER registers, which allow the guest to specify the base address of various data tables. Each register has a read-only type field indicating which table it is for and a read-write field where the guest can write in the base address (among other things). We currently allow the guest to write the writeable fields for all eight registers, even if the type field is 0 indicating "Unimplemented". This means the guest can provoke QEMU into asserting by writing an address into one of these unimplemented base registers, which bypasses the "if (!value) continue" check in extract_table_params() and lets us hit the assertion that the type field is one of the permitted table types. Prevent the assertion by not allowing the guest to write to the unimplemented base registers. This means their value will remain 0 and extract_table_params() will ignore them. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20220122182444.724087-12-peter.maydell@linaro.org --- hw/intc/arm_gicv3_its.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/intc/arm_gicv3_its.c b/hw/intc/arm_gicv3_its.c index b17f26312694..237198845d73 100644 --- a/hw/intc/arm_gicv3_its.c +++ b/hw/intc/arm_gicv3_its.c @@ -929,6 +929,10 @@ static bool its_writel(GICv3ITSState *s, hwaddr offset, if (!(s->ctlr & R_GITS_CTLR_ENABLED_MASK)) { index = (offset - GITS_BASER) / 8; + if (s->baser[index] == 0) { + /* Unimplemented GITS_BASERn: RAZ/WI */ + break; + } if (offset & 7) { value <<= 32; value &= ~GITS_BASER_RO_MASK; @@ -1025,6 +1029,10 @@ static bool its_writell(GICv3ITSState *s, hwaddr offset, */ if (!(s->ctlr & R_GITS_CTLR_ENABLED_MASK)) { index = (offset - GITS_BASER) / 8; + if (s->baser[index] == 0) { + /* Unimplemented GITS_BASERn: RAZ/WI */ + break; + } s->baser[index] &= GITS_BASER_RO_MASK; s->baser[index] |= (value & ~GITS_BASER_RO_MASK); }