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Bug#600299: linux-image-2.6.32-5-openvz-amd64: Openvz kernels appear to log unitialised memory to the console with log_buf_len=XX

On Fri, 2010-10-15 at 18:00 +0100, Tim Small wrote:
> Package: linux-2.6
> Version: 2.6.32-23
> Severity: normal
> When passing log_buf_len=2M to the kernel, the kernel logs nulls, or
> other aparently unitialised RAM to the console, and netconsole.

Any increase in log_buf_len will result in disaster, since OpenVZ will
continue using the old buffer pointer with the new length!

Please can you test this patch, following the instructions at


Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -198,6 +198,9 @@
 		spin_lock_irqsave(&logbuf_lock, flags);
 		log_buf_len = size;
 		log_buf = new_log_buf;
+#ifdef CONFIG_VE
+		ve0.log_buf = log_buf;
 		offset = start = min(con_start, log_start);
 		dest_idx = 0;
@@ -354,9 +357,9 @@
 		if (ve_log_buf == NULL)
 			goto out;
 		count = len;
+		spin_lock_irq(&logbuf_lock);
 		if (count > ve_log_buf_len)
 			count = ve_log_buf_len;
-		spin_lock_irq(&logbuf_lock);
 		if (count > ve_logged_chars)
 			count = ve_logged_chars;
 		if (do_clear)

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