printk silently truncates messages longer than 1024 - 1 bytes.
Implement overflow detection and append "$PRINTK_BUF_OVERFLOW$\n" to
truncated messages.
Signed-off-by: Tejun Heo <htejun@gmail.com>
---
kernel/printk.c | 15 ++++++++++++---
1 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 074a3ea..419cd47 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -42,6 +42,7 @@ void __attribute__((weak)) early_printk(const char *fmt, ...)
{
}
+#define PRINTK_BUF_LEN 1024
#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
/* printk's without a loglevel use this.. */
@@ -619,9 +620,10 @@ asmlinkage int vprintk(const char *fmt, va_list args)
static volatile unsigned int printk_cpu = UINT_MAX;
static const char printk_recursion_bug_msg [] =
KERN_CRIT "BUG: recent printk recursion!\n";
+ static const char overflow_tag[] = "$PRINTK_BUF_OVERFLOW$\n";
static int printk_recursion_bug;
static int log_level_unknown = 1;
- static char printk_buf[1024];
+ static char printk_buf[PRINTK_BUF_LEN + sizeof(overflow_tag) - 1];
unsigned long flags;
int printed_len = 0;
@@ -663,8 +665,15 @@ asmlinkage int vprintk(const char *fmt, va_list args)
printed_len = sizeof(printk_recursion_bug_msg);
}
/* Emit the output into the temporary buffer */
- printed_len += vscnprintf(printk_buf + printed_len,
- sizeof(printk_buf) - printed_len, fmt, args);
+ printed_len += vsnprintf(printk_buf + printed_len,
+ PRINTK_BUF_LEN - printed_len, fmt, args);
+
+ /* Check for overflow and tag the message if overflowed */
+ if (printed_len >= PRINTK_BUF_LEN) {
+ memcpy(printk_buf + PRINTK_BUF_LEN - 1, overflow_tag,
+ sizeof(overflow_tag));
+ printed_len = sizeof(printk_buf) - 1;
+ }
/*
* Copy the output into log_buf. If the caller didn't provide
--
1.5.2.4
--
