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Date: Wed, 27 Dec 2023 09:56:38 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Xiaobing Luo <luoxiaobing0926@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/cma: change print format of pointer in pr_debug()
 With %p, the pointer will be hashed and print (____ptrval____) instead.
Message-ID: <ZYv01tdp6/igAkJN@casper.infradead.org>
References: <20231227061825.116177-1-luoxiaobing0926@gmail.com>
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In-Reply-To: <20231227061825.116177-1-luoxiaobing0926@gmail.com>

On Wed, Dec 27, 2023 at 06:18:25AM +0000, Xiaobing Luo wrote:
>  [    0.070467] cma: cma_alloc(cma (____ptrval____), count 256, align 8)
>  [    0.073003] cma: cma_alloc(): returned (____ptrval____)
> 
> Use 0x%px instead of %p to print the pointer. Then the print will be like:
> 
>  [    0.054963] cma: cma_alloc(cma 0xffffffde9ad42a60, count 256, align 8)
>  [    0.057385] cma: cma_alloc(): returned 0xfffffffe003b0000

Please explain why we should leak this information to userspace,
making it easy for an attacker?