Re: [PATCH 1/4] printk: Allocate kernel log buffer earlier

From: Mike Travis
Date: Mon Feb 28 2011 - 14:29:06 EST

Ingo Molnar wrote:
* Yinghai Lu <yinghai@xxxxxxxxxx> wrote:

+ new_addr = memblock_alloc(new_log_buf_len, PAGE_SIZE);
+ if (new_addr != MEMBLOCK_ERROR)
+ new_log_buf = __va(new_addr);
+ else
+ new_log_buf = alloc_bootmem(new_log_buf_len);

alloc_bootmem() can fail, especially if someone uses a too large boot parameter value - and your code does not check for failure.

alloc_bootmem does panic when it can't allocate memory.

Ingo, we have a "uvconfig" script that sets up the boot parameters (there
are many that are needed to be very specific). It sets up the log_buf_len
to be 8M. We will never overflow memory with that.

And if someone is stupid enough to try and allocate a log buffer that
consumes more memory than they have, then they have a different kind of


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