From: Emilio G. Cota <cota@braap.org>
Date: Tue, 10 Apr 2018 15:13:54 +0000 (-0400)
Subject: target/mips: avoid integer overflow in next_page PC check
X-Git-Tag: v3.0.0-rc0~165^2~18
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6cd79443d33e6ba6b4c5b787eb713ca1cec56328;p=thirdparty%2Fqemu.git

target/mips: avoid integer overflow in next_page PC check

If the PC is in the last page of the address space, next_page_start
overflows to 0. Fix it.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Yongbok Kim <yongbok.kim@mips.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---

diff --git a/target/mips/translate.c b/target/mips/translate.c
index d05ee67e632..d8e717dacfc 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -20202,14 +20202,14 @@ void gen_intermediate_code(CPUState *cs, struct TranslationBlock *tb)
     CPUMIPSState *env = cs->env_ptr;
     DisasContext ctx;
     target_ulong pc_start;
-    target_ulong next_page_start;
+    target_ulong page_start;
     int num_insns;
     int max_insns;
     int insn_bytes;
     int is_slot;
 
     pc_start = tb->pc;
-    next_page_start = (pc_start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
+    page_start = pc_start & TARGET_PAGE_MASK;
     ctx.pc = pc_start;
     ctx.saved_pc = -1;
     ctx.singlestep_enabled = cs->singlestep_enabled;
@@ -20320,7 +20320,7 @@ void gen_intermediate_code(CPUState *cs, struct TranslationBlock *tb)
             break;
         }
 
-        if (ctx.pc >= next_page_start) {
+        if (ctx.pc - page_start >= TARGET_PAGE_SIZE) {
             break;
         }