[PATCH] [RFC] coredump: Ensure that the coredump helper has stdout and stderr

[PATCH] [RFC] coredump: Ensure that the coredump helper has stdout and stderr

[Richard Weinberger]

Currently only stdin is available in the coredump helper process.
If the process opens a file and then issues a printf(),
printf() will write to that opened file instead to a console.

Therefore open /dev/console and create fd 1 and 0 as init/main.c does.
sys_close(0) is only needed if sys_open() succeeds.
Before this patch it was in vain and returned always -EBADF because nobody
opened fd 0.

Signed-off-by: Richard Weinberger <richard@nod.at>
---
 fs/exec.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 574cf4d..2912fec 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2079,7 +2079,13 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
 
 	cp->file = files[1];
 
-	sys_close(0);
+	/* Ensure that the process has stdout and stderr */
+	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) == 0) {
+		sys_dup(0);
+		sys_dup(0);
+		sys_close(0);
+	}
+
 	fd_install(0, files[0]);
 	spin_lock(&cf->file_lock);
 	fdt = files_fdtable(cf);
-- 
1.7.11.5

Re: [PATCH] [RFC] coredump: Ensure that the coredump helper has stdout and stderr

[Richard Weinberger]

On 28.09.2012 18:32, Richard Weinberger wrote:
> Currently only stdin is available in the coredump helper process.
> If the process opens a file and then issues a printf(),
> printf() will write to that opened file instead to a console.
>
> Therefore open /dev/console and create fd 1 and 0 as init/main.c does.
> sys_close(0) is only needed if sys_open() succeeds.
> Before this patch it was in vain and returned always -EBADF because nobody
> opened fd 0.
>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>   fs/exec.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 574cf4d..2912fec 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -2079,7 +2079,13 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
>
>   	cp->file = files[1];
>
> -	sys_close(0);
> +	/* Ensure that the process has stdout and stderr */
> +	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) == 0) {
> +		sys_dup(0);
> +		sys_dup(0);
> +		sys_close(0);
> +	}
> +
>   	fd_install(0, files[0]);
>   	spin_lock(&cf->file_lock);
>   	fdt = files_fdtable(cf);
>

Ping?