From: He Zhe <zhe...@windriver.com>
log_buf_len_setup does not check input argument before passing it to
simple_strtoull. The argument would be a NULL pointer if "log_buf_len",
without its value, is set in command line and thus causes the following
panic.
PANIC: early exception 0xe3 IP 10:ffffffffaaeacd0d error 0 cr2 0x0
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted
4.19.0-rc4-yocto-standard+ #1
[ 0.000000] RIP: 0010:_parse_integer_fixup_radix+0xd/0x70
...
[ 0.000000] Call Trace:
[ 0.000000] simple_strtoull+0x29/0x70
[ 0.000000] memparse+0x26/0x90
[ 0.000000] log_buf_len_setup+0x17/0x22
[ 0.000000] do_early_param+0x57/0x8e
[ 0.000000] parse_args+0x208/0x320
[ 0.000000] ? rdinit_setup+0x30/0x30
[ 0.000000] parse_early_options+0x29/0x2d
[ 0.000000] ? rdinit_setup+0x30/0x30
[ 0.000000] parse_early_param+0x36/0x4d
[ 0.000000] setup_arch+0x336/0x99e
[ 0.000000] start_kernel+0x6f/0x4ee
[ 0.000000] x86_64_start_reservations+0x24/0x26
[ 0.000000] x86_64_start_kernel+0x6f/0x72
[ 0.000000] secondary_startup_64+0xa4/0xb0
This patch adds a check to prevent the panic and a check to report if someone is
setting it over 4G.
Signed-off-by: He Zhe <zhe...@windriver.com>
Cc: sta...@vger.kernel.org
Cc: pmla...@suse.com
Cc: sergey.senozhat...@gmail.com
Cc: rost...@goodmis.org
---
v2:
Split out the addition of pr_fmt and the unsigned update
v3:
Remove error message for NULL pointer
Add check and error message for over 4G use
kernel/printk/printk.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9bf5404..1c932b6 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1037,18 +1037,29 @@ 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 size = memparse(str, &str);
+ u64 size;
+
+ if (!str) {
+ return -EINVAL;
+ }
+
+ size = memparse(str, &str);
log_buf_len_update(size);
--
2.7.4
