printk: fix possible printk overrun

cf3680b9 · Tejun Heo <[email protected]> · 2008-02-14 10:32:07 +09:00

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.

[ [email protected]:

  bug was introduced by me via:

   commit 32a76006683f7b28ae3cc491da37716e002f198e
   Author: Ingo Molnar <[email protected]>
   Date:   Fri Jan 25 21:07:58 2008 +0100

       printk: make printk more robust by not allowing recursion
]

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: cf3680b90c7842cf91ed857ac4528f4e057da366
Parents: bfa274e2

Changes

1 files changed · +1 −1

File	Status	Add	Del	Content
kernel/printk.c	modified	+1	−1	View file

kernel/printk.c

View file

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