[Qemu-devel] [PATCH v1 1/6] target/riscv: avoid integer overflow in next_page PC check

[Michael Clark <mjc@sifive.com>]

From: "Emilio G. Cota" <cota@braap.org>

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

Reported-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Michael Clark <mjc@sifive.com>
Acked-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Michael Clark <mjc@sifive.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Signed-off-by: Emilio G. Cota <cota@braap.org>
---
 target/riscv/translate.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index c0e6a044d383..a98033ca77ca 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -1850,11 +1850,11 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb)
     CPURISCVState *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;
     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;
 
     /* once we have GDB, the rest of the translate.c implementation should be
@@ -1904,7 +1904,7 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb)
         if (cs->singlestep_enabled) {
             break;
         }
-        if (ctx.pc >= next_page_start) {
+        if (ctx.pc - page_start >= TARGET_PAGE_SIZE) {
             break;
         }
         if (tcg_op_buf_full()) {
-- 
2.7.0