On Sat, 22 Sep 2018 23:40:51 +0800
<zhe...@windriver.com> wrote:
> 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.
>
> Signed-off-by: He Zhe <zhe...@windriver.com>
> Cc: sta...@vger.kernel.org
I just tried this on a 2.6.32 kernel, and it crashes there. I guess
this goes farther back than git history goes.
Perhaps it should be commented that this bug has been here since
creation of (git) time.
> 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
Which unsigned update? As it does switch to unsigned to "unsigned int",
but that change is fine to me with this.
> v3:
> Use more clear error info
> Change unsigned to unsigned in to avoid checkpatch.pl warning
>
> kernel/printk/printk.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 9bf5404..d9821c0 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1048,7 +1048,14 @@ static void __init log_buf_len_update(unsigned 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);
> + unsigned int size;
I'm OK with the int update too, as its low risk.
Acked-by: Steven Rostedt (VMware) <rost...@goodmis.org>
-- Steve
> +
> + if (!str) {
> + pr_err("boot command line parameter value not provided\n");
> + return -EINVAL;
> + }
> +
> + size = memparse(str, &str);
>
> log_buf_len_update(size);
>
