printk: fix possible printk overrun
printk recursion detection prepends message to printk_buf and offsets
printk_buf when actual message is printed but it forgets to trim buffer
length accordingly. This can result in overrun in extreme cases. Fix it.
[ mingo@elte.hu:
bug was introduced by me via:
commit 32a76006683f7b28ae3cc491da37716e002f198e
Author: Ingo Molnar <mingo@elte.hu>
Date: Fri Jan 25 21:07:58 2008 +0100
printk: make printk more robust by not allowing recursion
]
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/printk.c b/kernel/printk.c
index bee3610..9adc2a4 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -666,7 +666,7 @@
}
/* Emit the output into the temporary buffer */
printed_len += vscnprintf(printk_buf + printed_len,
- sizeof(printk_buf), fmt, args);
+ sizeof(printk_buf) - printed_len, fmt, args);
/*
* Copy the output into log_buf. If the caller didn't provide