Re: [PATCH v2 2/2] sysvipc: Return EINVAL for invalid shmctl commands

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

If no one opposes I will commit this shortly (with Andreas redundant
'command' word in comments).

On 05/10/2020 14:11, Adhemerval Zanella wrote:
> Changes from previous version:
> 
>  - Handle missing SHM_STAT_ANY on __shmctl64.
> 
> --
> 
> It avoids regressions on possible future commands that might require
> additional libc support.  The downside is new commands added by newer
> kernels will need further glibc support.
> 
> Checked on x86_64-linux-gnu and i686-linux-gnu (Linux v4.15 and v5.4).
> ---
>  sysdeps/unix/sysv/linux/shmctl.c | 42 ++++++++++++++++++++++++--------
>  sysvipc/test-sysvipc.h           | 25 +++++++++++++++++++
>  sysvipc/test-sysvshm.c           |  5 ++++
>  3 files changed, 62 insertions(+), 10 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/shmctl.c b/sysdeps/unix/sysv/linux/shmctl.c
> index 1d19a798b1..73f0b7326f 100644
> --- a/sysdeps/unix/sysv/linux/shmctl.c
> +++ b/sysdeps/unix/sysv/linux/shmctl.c
> @@ -88,25 +88,47 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
>  {
>  #if __IPC_TIME64
>    struct kernel_shmid64_ds kshmid, *arg = NULL;
> -  if (buf != NULL)
> +#else
> +  shmctl_arg_t *arg;
> +#endif
> +
> +  switch (cmd)
>      {
> -      /* This is a Linux extension where kernel expects either a
> -	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
> -      if (cmd == IPC_INFO || cmd == SHM_INFO)
> -	arg = (struct kernel_shmid64_ds *) buf;
> -      else
> +    case IPC_RMID:
> +      arg = NULL;
> +      break;
> +
> +    case IPC_SET:
> +    case IPC_STAT:
> +    case SHM_STAT:
> +    case SHM_STAT_ANY:
> +#if __IPC_TIME64
> +      if (buf != NULL)
>  	{
>  	  shmid64_to_kshmid64 (buf, &kshmid);
>  	  arg = &kshmid;
>  	}
> -    }
>  # ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
> -  if (cmd == IPC_SET)
> -    arg->shm_perm.mode *= 0x10000U;
> +      if (cmd == IPC_SET)
> +        arg->shm_perm.mode *= 0x10000U;
>  # endif
>  #else
> -  shmctl_arg_t *arg = buf;
> +      arg = buf;
>  #endif
> +      break;
> +
> +    case IPC_INFO:
> +    case SHM_INFO:
> +      /* This is a Linux extension where kernel expects either a
> +	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
> +      arg = (__typeof__ (arg)) buf;
> +      break;
> +
> +    default:
> +      __set_errno (EINVAL);
> +      return -1;
> +    }
> +
>  
>    int ret = shmctl_syscall (shmid, cmd, arg);
>    if (ret < 0)
> diff --git a/sysvipc/test-sysvipc.h b/sysvipc/test-sysvipc.h
> index 21ef6c6565..179f5e8cc9 100644
> --- a/sysvipc/test-sysvipc.h
> +++ b/sysvipc/test-sysvipc.h
> @@ -107,4 +107,29 @@ first_msg_invalid_cmd (void)
>    return invalid;
>  }
>  
> +/* Return the first invalid command SysV IPC command for shared memory.  */
> +static inline int
> +first_shm_invalid_cmd (void)
> +{
> +  const int shm_cmds[] = {
> +    SHM_STAT,
> +    SHM_INFO,
> +#ifdef SHM_STAT_ANY
> +    SHM_STAT_ANY,
> +#endif
> +  };
> +
> +  int invalid = first_common_invalid_cmd ();
> +  for (int i = 0; i < array_length (shm_cmds); i++)
> +    {
> +      if (invalid == shm_cmds[i])
> +	{
> +	  invalid++;
> +	  i = 0;
> +	}
> +    }
> +
> +  return invalid;
> +}
> +
>  #endif /* _TEST_SYSV_H  */
> diff --git a/sysvipc/test-sysvshm.c b/sysvipc/test-sysvshm.c
> index f083fd280b..a1b8b4823e 100644
> --- a/sysvipc/test-sysvshm.c
> +++ b/sysvipc/test-sysvshm.c
> @@ -25,6 +25,8 @@
>  #include <sys/ipc.h>
>  #include <sys/shm.h>
>  
> +#include <test-sysvipc.h>
> +
>  #include <support/support.h>
>  #include <support/check.h>
>  #include <support/temp_file.h>
> @@ -81,6 +83,9 @@ do_test (void)
>        FAIL_EXIT1 ("shmget failed (errno=%d)", errno);
>      }
>  
> +  TEST_COMPARE (shmctl (shmid, first_shm_invalid_cmd (), NULL), -1);
> +  TEST_COMPARE (errno, EINVAL);
> +
>    /* Get shared memory kernel information and do some sanity checks.  */
>    struct shmid_ds shminfo;
>    if (shmctl (shmid, IPC_STAT, &shminfo) == -1)
>