[PATCH] arm64: compat: fix compat types affecting struct compat_elf_prpsinfo

[Catalin Marinas]

On Tue, Oct 14, 2014 at 06:55:05AM +0100, Victor Kamensky wrote:
> The compat_elf_prpsinfo structure does not match the arch/arm struct
> elf_pspsinfo definition. As result NT_PRPSINFO note in core file
> created by arm64 kernel for aarch32 (compat) process has wrong size.
> So gdb cannot display command that caused process crash.
> 
> Fix is to change size of __compat_uid_t, __compat_gid_t so it would
> match size of similar fields in arch/arm case.
> 
> Signed-off-by: Victor Kamensky <victor.kamensky at linaro.org>
> ---
>  arch/arm64/include/asm/compat.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
> index 253e33b..56de5aa 100644
> --- a/arch/arm64/include/asm/compat.h
> +++ b/arch/arm64/include/asm/compat.h
> @@ -37,8 +37,8 @@ typedef s32		compat_ssize_t;
>  typedef s32		compat_time_t;
>  typedef s32		compat_clock_t;
>  typedef s32		compat_pid_t;
> -typedef u32		__compat_uid_t;
> -typedef u32		__compat_gid_t;
> +typedef u16		__compat_uid_t;
> +typedef u16		__compat_gid_t;
>  typedef u16		__compat_uid16_t;
>  typedef u16		__compat_gid16_t;
>  typedef u32		__compat_uid32_t;

__compat_uid_t is defined to match the arm32 uid_t and that would be
__kernel_uid32_t (or __compat_uid32_t). So this is the correct fix.

The problem is that elf_prpsinfo uses __kernel_uid_t which arm32 defines
as (unsigned short) while compat_elf_prspinfo uses __compat_uid_t which
is 32-bit. In reality compat_uid_t is different from the arm32
kernel_uid_t (other 32-bit architectures may use a 32-bit kernel_uid_t).

So we either define a compat_kernel_uid_t or allow per-arch
compat_elf_prspinfo. I would go for the former and also grep the kernel
for other uses of compat_uid_t assuming the same size as the 32-bit
__kernel_uid_t.

-- 
Catalin