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From: Shubhang <sh@gentwo.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Uladzislau Rezki <urezki@gmail.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	 Shubhang Kaushik <shubhang@os.amperecomputing.com>,
	 "Christoph Lameter (Ampere)" <cl@gentwo.org>,
	linux-mm@kvack.org,  linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] mm/vmalloc: reject overflowing vm_map_ram page counts
Date: Mon, 9 Nov 2026 17:49:23 -0800 (PST)	[thread overview]
Message-ID: <d6fe4283-0d6c-5fec-2252-af68b2c46b83@gentwo.org> (raw)
In-Reply-To: <20261101201659.c6c07375429df81081ce8b0f@linux-foundation.org>

Hi Andrew,

On Sun, 1 Nov 2026, Andrew Morton wrote:
>
> Is there a case where userspace can actually hit this, or is it a
> theoretical case which can't actually be encountered, or something else?
>

Reaching vm_map_ram() with an overflowing count from userspace is real
(as noted in the udmabuf path earlier), but actually hitting an oops or
corruption remains theoretical because in-tree callers don't access
beyond the truncated size.

The changelog described what happens if a caller does access the full
requested range. I can send a v3 clarifying that the failure mode 
is theoretical if you'd prefer.

Thanks,
Shubhang Kaushik

      reply	other threads:[~2026-11-10  1:49 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-23  6:43 Shubhang Kaushik (Ampere)
2026-10-30  3:55 ` Andrew Morton
2026-10-30  6:23 ` Dev Jain
2026-11-02  4:16 ` Andrew Morton
2026-11-10  1:49   ` Shubhang [this message]

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