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

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Message-Id: <1348849971-23412-1-git-send-email-richard@nod.at>
Date:	Fri, 28 Sep 2012 18:32:51 +0200
From:	Richard Weinberger <richard@....at>
To:	viro@...iv.linux.org.uk
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Richard Weinberger <richard@....at>
Subject: [PATCH] [RFC] coredump: Ensure that the coredump helper has stdout and stderr

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@....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

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