[CRIU] [PATCH] x86/kdat: Check PTRACE_TRACEME return value

[Andrei Vagin]

Applied, thanks!

On Tue, Feb 27, 2018 at 01:42:55PM +0000, Dmitry Safonov wrote:
> Coverity has informed:
> 
> *** CID 188251:  Error handling issues  (CHECKED_RETURN)
> /criu/arch/x86/crtools.c: 196 in kdat_x86_has_ptrace_fpu_xsave_bug_child()
> 190             return 0;
> 191     }
> 192     #endif
> 193
> 194     static int kdat_x86_has_ptrace_fpu_xsave_bug_child(void *arg)
> 195     {
> >>>     CID 188251:  Error handling issues  (CHECKED_RETURN)
> >>>     Calling "ptrace" without checking return value (as is done elsewhere 46 out of 51 times).
> 196             ptrace(PTRACE_TRACEME, 0, 0, 0);
> 197             kill(getpid(), SIGSTOP);
> 198             pr_err("Continue after SIGSTOP.. Urr what?\n");
> 199             _exit(1);
> 200     }
> 201
> 
> Also added checks for kill() and waitpid().
> 
> Signed-off-by: Dmitry Safonov <dima at arista.com>
> ---
>  criu/arch/x86/kerndat.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/criu/arch/x86/kerndat.c b/criu/arch/x86/kerndat.c
> index a67017d3456e..006196829c89 100644
> --- a/criu/arch/x86/kerndat.c
> +++ b/criu/arch/x86/kerndat.c
> @@ -178,8 +178,14 @@ int kdat_compatible_cr(void)
>  
>  static int kdat_x86_has_ptrace_fpu_xsave_bug_child(void *arg)
>  {
> -	ptrace(PTRACE_TRACEME, 0, 0, 0);
> -	kill(getpid(), SIGSTOP);
> +	if (ptrace(PTRACE_TRACEME, 0, 0, 0)) {
> +		pr_perror("%d: ptrace(PTRACE_TRACEME) failed", getpid());
> +		_exit(1);
> +	}
> +
> +	if (kill(getpid(), SIGSTOP))
> +		pr_perror("%d: failed to kill myself", getpid());
> +
>  	pr_err("Continue after SIGSTOP.. Urr what?\n");
>  	_exit(1);
>  }
> @@ -243,7 +249,10 @@ int kdat_x86_has_ptrace_fpu_xsave_bug(void)
>  	ret = !xsave.i387.mxcsr;
>  
>  out_kill:
> -	kill(child, SIGKILL);
> -	waitpid(child, &stat, 0);
> +	if (kill(child, SIGKILL))
> +		pr_perror("Failed to kill my own child");
> +	if (waitpid(child, &stat, 0) < 0)
> +		pr_perror("Failed wait for a dead child");
> +
>  	return ret;
>  }
> -- 
> 2.13.6
> 
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