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Re: [Qemu-devel] [PATCH] target-arm/translate-a64: Fix wrong mmu_idx usa


From: Greg Bellows
Subject: Re: [Qemu-devel] [PATCH] target-arm/translate-a64: Fix wrong mmu_idx usage for LDT/STT
Date: Tue, 20 Jan 2015 08:31:43 -0600



On Tue, Jan 20, 2015 at 7:58 AM, Peter Maydell <address@hidden> wrote:
The LDT/STT (load/store unprivileged) instruction decode was using
the wrong MMU index value. This meant that instead of these insns
being "always access as if user-mode regardless of current privilege"
they were "always access as if kernel-mode regardless of current
privilege". This went unnoticed because AArch64 Linux doesn't use
these instructions.

Cc: address@hidden

Signed-off-by: Peter Maydell <address@hidden>
---
I'm not counting this as a security issue because I'm assuming
nobody treats TCG guests as a security boundary (certainly I
would not recommend doing so...)
---
 target-arm/translate-a64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 80d2359..dac2f63 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -2107,7 +2107,7 @@ static void disas_ldst_reg_imm9(DisasContext *s, uint32_t insn)
         }
     } else {
         TCGv_i64 tcg_rt = cpu_reg(s, rt);
-        int memidx = is_unpriv ? 1 : get_mem_index(s);
+        int memidx = is_unpriv ? MMU_USER_IDX : get_mem_index(s);

         if (is_store) {
             do_gpr_st_memidx(s, tcg_rt, tcg_addr, size, memidx);
--
1.9.1




​Reviewed-by: Greg Bellows <address@hidden>​
 


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