linux-kernel - Re: [PATCH v2 1/2] printk: Fix panic caused by passing log_buf

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Message-ID: <20180919023932.GA14090@jagdpanzerIV>
Date:   Wed, 19 Sep 2018 11:39:32 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     He Zhe <zhe.he@...driver.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        pmladek@...e.com, sergey.senozhatsky@...il.com,
        rostedt@...dmis.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] printk: Fix panic caused by passing log_buf_len
 to command line

On (09/19/18 10:27), He Zhe wrote:
> On 2018年09月19日 09:50, Sergey Senozhatsky wrote:
> > On (09/19/18 01:17), zhe.he@...driver.com wrote:
> >> @@ -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 size;
> > 	unsigned int size;
> 
> This is in v1 but then Steven suggested that it should be split out
> and only keep the pure fix part here.

Ah, I see.

Hmm... memparse() returns u64 value. A user *probably* can ask the kernel
to allocate log_buf larger than 'unsigned int'.

So may be I'd do two fixes here:

 First  - switch to u64 size.
 Second - check for NULL str.


Steven, Petr, what do you think?

	-ss