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Peter Anvin" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jennifer Miller , Tiffany Bao , Ruoyu Wang , Adam Doupe , Kyle Zeng , Yan Shoshitaishvili Subject: Re: [PATCH v2] mm/vmalloc: widen guard region to defeat ENTER-based stack pivot Message-ID: <20260701071945.GL48970@noisy.programming.kicks-ass.net> References: <20260629214712.1198680-1-xmei5@asu.edu> <4e96acf4-25e7-4f30-8455-f9b3f49062be@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 70CA340007 X-Stat-Signature: 6gqtgkweoks79cmae533wiq3i66cpken X-HE-Tag: 1782890390-58412 X-HE-Meta: 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 KFTZ1Mbc VeDVNxcX9o0GEzRqbLi0KfgUNBhclmy9ajo8WkVxTFv+QSMCLsBrxyECniCxG2PvWk8PITXfKOaJ6gpDenzjLf7aNQrav+qdWkTDBx98ua9Tyeky/sMqVOPgo08CE6CldUSoH6lCm4TEtWhAkKn3vB+v52UUeAkijrL6E6vPrvpuoqDQ/06iBuczhAtXQpF52j9SwSWsU0ttAVI5KVk/1Sy0XXbB9lPh8gRlV+hw65R1tTPkHmq60pJQ32MbbapLVuFFlQdMqj88HYJzHmDEkptRCVl8B/GvS5eksGMBiQcUzgVaOb3pxBFde8g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 30, 2026 at 07:01:48AM -0700, Dave Hansen wrote: > On 6/29/26 18:22, Xiang Mei wrote: > >> Please don't even try to send a v3 without addressing this. > > This is a demo exploiting CVE-2026-31419 with this technique: > > https://github.com/google/security-research/pull/397 > > Thanks for sharing that. That's really good info. > > But what I want to hear a bit more about is why this new guard region is > a good, generic mitigation. Does it help mitigate a whole class of > vulnerabilities? > > I think you're making the claim that this ENTER technique takes what > would normally just be a DoS and makes it fully exploitable. Does this > happen for a lot of DoS bugs? Or is CVE-2026-31419 very unusual and this > stack guard gunk won't ever be useful again? AFAICT all it really does it make it easier to set up a ROP chain. I don't think ROP is unfeasible without it.