[PATCH UPDATED] printk: fix possible printk buffer overrun introducedwith recursion check

[Tejun Heo]

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 buffer overrun in
extreme cases.  Fix it.

Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxx>
---
Splitted out fix portion.

 kernel/printk.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 	}
 	/* 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
--
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