[Qemu-devel] [PATCH v3] RISC-V: Fix riscv_isa_string memory size bug

[Michael Clark <mjc@sifive.com>]

This version uses a constant size memory buffer sized for
the maximum possible ISA string length. It also uses g_new
instead of g_new0, uses more efficient logic to append
extensions and adds manual zero termination of the string.

Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Michael Clark <mjc@sifive.com>
---
 target/riscv/cpu.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 4851890..298abbd 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -391,16 +391,16 @@ static const TypeInfo riscv_cpu_type_info = {
 char *riscv_isa_string(RISCVCPU *cpu)
 {
     int i;
-    size_t maxlen = 5 + ctz32(cpu->env.misa);
-    char *isa_string = g_new0(char, maxlen);
-    snprintf(isa_string, maxlen, "rv%d", TARGET_LONG_BITS);
+    const size_t maxlen = sizeof("rv128") + sizeof(riscv_exts) + 1;
+    char *isa_str = g_new(char, maxlen);
+    char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", TARGET_LONG_BITS);
     for (i = 0; i < sizeof(riscv_exts); i++) {
         if (cpu->env.misa & RV(riscv_exts[i])) {
-            isa_string[strlen(isa_string)] = riscv_exts[i] - 'A' + 'a';
-
+            *p++ = riscv_exts[i] - 'A' + 'a';
         }
     }
-    return isa_string;
+    *p = '\0';
+    return isa_str;
 }
 
 void riscv_cpu_list(FILE *f, fprintf_function cpu_fprintf)
-- 
2.7.0