[PATCH v5 4/4] printk: Give error on attempt to set log buffer length to over 4G

From: zhe.he
Date: Sat Sep 29 2018 - 12:46:55 EST


From: He Zhe <zhe.he@xxxxxxxxxxxxx>

Give explicit error for users who want to use larger log buffer.

Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
Cc: pmladek@xxxxxxxx
Cc: sergey.senozhatsky@xxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
---
kernel/printk/printk.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b84aac0..5ccfd5d 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1039,18 +1039,23 @@ void log_buf_vmcoreinfo_setup(void)
static unsigned long __initdata new_log_buf_len;

/* we practice scaling the ring buffer by powers of 2 */
-static void __init log_buf_len_update(unsigned size)
+static void __init log_buf_len_update(u64 size)
{
+ if (size > UINT_MAX) {
+ size = UINT_MAX;
+ pr_err("log_buf over 4G is not supported.\n");
+ }
+
if (size)
size = roundup_pow_of_two(size);
if (size > log_buf_len)
- new_log_buf_len = size;
+ new_log_buf_len = (unsigned long)size;
}

/* save requested log_buf_len since it's too early to process it */
static int __init log_buf_len_setup(char *str)
{
- unsigned int size;
+ u64 size;

if (!str)
return -EINVAL;
--
2.7.4