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From: Tejun Heo <>
To: Ingo Molnar <>
Cc: Linus Torvalds <>,
	Randy Dunlap <>,
	Linux Kernel <>
Subject: [PATCH UPDATED] printk: fix possible printk buffer overrun introduced with recursion check
Date: Thu, 14 Feb 2008 10:32:07 +0900	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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 <>
Acked-by: Ingo Molnar <>
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

  reply	other threads:[~2008-02-14  1:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-13  8:46 [PATCH REPOST] " Tejun Heo
2008-02-13 12:45 ` Ingo Molnar
2008-02-14  0:11   ` Tejun Heo
2008-02-14  1:32     ` Tejun Heo [this message]
2008-02-14  1:39     ` [PATCH] printk: clean up recursion check related static variables Tejun Heo

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