Re: [Qemu-devel] [PATCH] target-mips: fix resource leak reported by Coverity

[Aurelien Jarno <aurelien@aurel32.net>]

On 2015-07-14 11:08, Leon Alrae wrote:
> UHI assert and link operations call lock_user_string() twice to obtain two
> strings pointed by gpr[4] and gpr[5]. If the second lock_user_string()
> fails, then the first one won't get freed. Fix this by introducing another
> macro responsible for obtaining two strings and handling allocation
> failure.
> 
> Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
> ---
>  target-mips/mips-semi.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/target-mips/mips-semi.c b/target-mips/mips-semi.c
> index 1162c76..5050940 100644
> --- a/target-mips/mips-semi.c
> +++ b/target-mips/mips-semi.c
> @@ -220,6 +220,23 @@ static int copy_argn_to_target(CPUMIPSState *env, int arg_num,
>          }                                       \
>      } while (0)
>  
> +#define GET_TARGET_STRINGS_2(p, addr, p2, addr2)        \
> +    do {                                                \
> +        p = lock_user_string(addr);                     \
> +        if (!p) {                                       \
> +            gpr[2] = -1;                                \
> +            gpr[3] = EFAULT;                            \
> +            goto uhi_done;                              \
> +        }                                               \
> +        p2 = lock_user_string(addr2);                   \
> +        if (!p2) {                                      \
> +            unlock_user(p, addr, 0);                    \
> +            gpr[2] = -1;                                \
> +            gpr[3] = EFAULT;                            \
> +            goto uhi_done;                              \
> +        }                                               \
> +    } while (0)
> +
>  #define FREE_TARGET_STRING(p, gpr)              \
>      do {                                        \
>          unlock_user(p, gpr, 0);                 \
> @@ -322,8 +339,7 @@ void helper_do_semihosting(CPUMIPSState *env)
>          FREE_TARGET_STRING(p, gpr[4]);
>          break;
>      case UHI_assert:
> -        GET_TARGET_STRING(p, gpr[4]);
> -        GET_TARGET_STRING(p2, gpr[5]);
> +        GET_TARGET_STRINGS_2(p, gpr[4], p2, gpr[5]);
>          printf("assertion '");
>          printf("\"%s\"", p);
>          printf("': file \"%s\", line %d\n", p2, (int)gpr[6]);
> @@ -341,8 +357,7 @@ void helper_do_semihosting(CPUMIPSState *env)
>          break;
>  #ifndef _WIN32
>      case UHI_link:
> -        GET_TARGET_STRING(p, gpr[4]);
> -        GET_TARGET_STRING(p2, gpr[5]);
> +        GET_TARGET_STRINGS_2(p, gpr[4], p2, gpr[5]);
>          gpr[2] = link(p, p2);
>          gpr[3] = errno_mips(errno);
>          FREE_TARGET_STRING(p2, gpr[5]);

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net