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Commit cf3680b9 authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
Browse files

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 32a76006
   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: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bfa274e2

kernel/printk.c

+1 −1
Original line number Diff line number Diff line
@@ -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