linux-kernel - Re: cat /dev/snapshot == OOPs

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Message-Id: <200706101933.53647.rjw@sisk.pl>
Date:	Sun, 10 Jun 2007 19:33:53 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Arkadiusz Miskiewicz <arekm@...en.pl>
Cc:	linux-kernel@...r.kernel.org,
	"S.Çağlar Onur" <caglar@...dus.org.tr>
Subject: Re: cat /dev/snapshot == OOPs

On Sunday, 10 June 2007 15:42, Arkadiusz Miskiewicz wrote:
> Hello,
> 
> Is this desired behaviour?

Obviously not.

> $ sudo cat /dev/snapshot
> 
> ended with:
> 
> [54498.464550] device-mapper: ioctl: 4.11.0-ioctl (2006-10-12) initialised: 
> dm-devel@...hat.com
> [56592.077674] swsusp: Basic memory bitmaps created
> [56592.084340] BUG: unable to handle kernel NULL pointer dereference at 
> virtual address 0000000c

Can you please try the appended patch?

Rafael


Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 kernel/power/user.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6.22-rc4/kernel/power/user.c
===================================================================
--- linux-2.6.22-rc4.orig/kernel/power/user.c	2007-06-10 19:33:36.000000000 +0200
+++ linux-2.6.22-rc4/kernel/power/user.c	2007-06-10 19:35:59.000000000 +0200
@@ -99,6 +99,8 @@ static ssize_t snapshot_read(struct file
 	ssize_t res;
 
 	data = filp->private_data;
+	if (!data->ready)
+		return -ENODATA;
 	res = snapshot_read_next(&data->handle, count);
 	if (res > 0) {
 		if (copy_to_user(buf, data_of(data->handle), res))
@@ -163,7 +165,7 @@ static int snapshot_ioctl(struct inode *
 		break;
 
 	case SNAPSHOT_UNFREEZE:
-		if (!data->frozen)
+		if (!data->frozen || data->ready)
 			break;
 		mutex_lock(&pm_mutex);
 		thaw_processes();
-
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