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.
While at it, make printk_recursion_bug_msg static and move static
variables for recursion check into vprintk().
Signed-off-by: Tejun Heo <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
---
Eeeek, forgot to cc lkml last time. Re-sending. Sorry about the
noise.
kernel/printk.c | 14 ++++++--------
1 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index bee3610..074a3ea 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -613,15 +613,13 @@ asmlinkage int printk(const char *fmt, ...)
return r;
}
-/* cpu currently holding logbuf_lock */
-static volatile unsigned int printk_cpu = UINT_MAX;
-
-const char printk_recursion_bug_msg [] =
- KERN_CRIT "BUG: recent printk recursion!\n";
-static int printk_recursion_bug;
-
asmlinkage int vprintk(const char *fmt, va_list args)
{
+ /* cpu currently holding logbuf_lock */
+ static volatile unsigned int printk_cpu = UINT_MAX;
+ static const char printk_recursion_bug_msg [] =
+ KERN_CRIT "BUG: recent printk recursion!\n";
+ static int printk_recursion_bug;
static int log_level_unknown = 1;
static char printk_buf[1024];
@@ -666,7 +664,7 @@ 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
--
1.5.2.4
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