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AJvYcCUOJv1x8XNTni74nStQiO8aSxOwnZ7YPSQBNt/e0me1TMdgJfCA8orgCYymAj4hf7MoqkZ3va5vpg==@kvack.org X-Gm-Message-State: AOJu0YxG+nK5y4jsNSuoyikIgiNBHi6nX847+VJPnaZq4CiZ4UPwZA94 r4YzvcBqDFAI7oyQ3jbC0zGKlFvspkiqaHAn3zCtVRdFLKVSnpcYJzXI16xpqN/Wsh12rpE5lyb bvE3tRRexcHaSEbfZzaiLlXZh5y3jp2oFj9PmbEH/ X-Gm-Gg: ASbGnctYTpKZfdntC3yLWLGVfwgqNS7tcCdAXN3D1tuRh0Ge2BaKXSQPVkxtqwSaEcY K3mBkRj2WBb2RC8q8BIK2W2OHsONOotAnvIx0Hhho9FjtFTxQGPLHzm5lkLJVRCSTYKhbf0c0VX BUoSbcExBDbb9SZBI7l0IpTmTZOFJ7wG++0Bs1aNFUPxB9znlgCIUjM9Nm9Y/i+XPcIJPHikK4R MKN8sWj/6N/fpcpSJCz8aVZXiyzTL8kY/BNW6lxoyHvUrLe2m70J9qlPGB1+JHfRAmeAYzWoak6 MaaoqtQIb8ArAyAi1myEUmtlhBSVuRe4bGRg X-Google-Smtp-Source: AGHT+IFHyI5tV3uPkHfzZQDwtLCu1xXfZdNpjQHEIN8gqbseljKndHdCHWJHLu5LbqQguzv8YlVvlOC2YwOH7fkw7n0= X-Received: by 2002:a05:622a:205:b0:4ec:f151:6559 with SMTP id d75a77b69052e-4eda4ec1851mr145606591cf.27.1762852474078; Tue, 11 Nov 2025 01:14:34 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Alexander Potapenko Date: Tue, 11 Nov 2025 10:13:57 +0100 X-Gm-Features: AWmQ_bknFBa8gAhB6UE8n7ZlyUgSKcguUN9eypJruwNRSxK5vCFPizbRNuQ2qaE Message-ID: Subject: Re: [PATCH v6 09/18] mm/execmem: Untag addresses in EXECMEM_ROX related pointer arithmetic To: Maciej Wieczor-Retman Cc: xin@zytor.com, peterz@infradead.org, kaleshsingh@google.com, kbingham@kernel.org, akpm@linux-foundation.org, nathan@kernel.org, ryabinin.a.a@gmail.com, dave.hansen@linux.intel.com, bp@alien8.de, morbo@google.com, jeremy.linton@arm.com, smostafa@google.com, kees@kernel.org, baohua@kernel.org, vbabka@suse.cz, justinstitt@google.com, wangkefeng.wang@huawei.com, leitao@debian.org, jan.kiszka@siemens.com, fujita.tomonori@gmail.com, hpa@zytor.com, urezki@gmail.com, ubizjak@gmail.com, ada.coupriediaz@arm.com, nick.desaulniers+lkml@gmail.com, ojeda@kernel.org, brgerst@gmail.com, elver@google.com, pankaj.gupta@amd.com, mark.rutland@arm.com, trintaeoitogc@gmail.com, jpoimboe@kernel.org, thuth@redhat.com, pasha.tatashin@soleen.com, dvyukov@google.com, jhubbard@nvidia.com, catalin.marinas@arm.com, yeoreum.yun@arm.com, mhocko@suse.com, lorenzo.stoakes@oracle.com, samuel.holland@sifive.com, vincenzo.frascino@arm.com, bigeasy@linutronix.de, surenb@google.com, ardb@kernel.org, Liam.Howlett@oracle.com, nicolas.schier@linux.dev, ziy@nvidia.com, kas@kernel.org, tglx@linutronix.de, mingo@redhat.com, broonie@kernel.org, corbet@lwn.net, andreyknvl@gmail.com, maciej.wieczor-retman@intel.com, david@redhat.com, maz@kernel.org, rppt@kernel.org, will@kernel.org, luto@kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 831EC80003 X-Stat-Signature: kmoqfng9fjex9to9jqkimgckmo5mxnif X-HE-Tag: 1762852475-268634 X-HE-Meta: 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 zqx995/R ABmFv0hmPJW7xDwk9VQCDARRVmMvcTqGSf8yl8HisZP/XFosFJvpyz+JWDKUFXB7wzc2jCtn9Gdiaa9rr0uaQ8Xeq0TNbQKuQFYGbYvzLnUV1BxRSbcBjqAA8ZUYSOiViCr7576GvgAk7pDYlxYV3dkvlan1BHC53dsDzCG85xCZN6oG1SOeGniftDC4RoF9ZgT+QxrBo8kt3EN0AYg93C+SfRRPqZDcecs34qdil3fBO8pnMZfEob6serjMN4stkAfZtTw8u/HOA9PnY5b0n1fILoJsb0MxaizLz/K4VA9oAo0m6FIW2CukEQaJknfClnaBQ5xcsguSJLX9sdLCrQsMEcyARgO3O0nrGmFzDJe3W4u4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Oct 29, 2025 at 8:08=E2=80=AFPM Maciej Wieczor-Retman wrote: > > From: Maciej Wieczor-Retman > > ARCH_HAS_EXECMEM_ROX was re-enabled in x86 at Linux 6.14 release. > vm_reset_perms() calculates range's start and end addresses using min() > and max() functions. To do that it compares pointers but, with KASAN > software tags mode enabled, some are tagged - addr variable is, while > start and end variables aren't. This can cause the wrong address to be > chosen and result in various errors in different places. > > Reset tags in the address used as function argument in min(), max(). > > execmem_cache_add() adds tagged pointers to a maple tree structure, > which then are incorrectly compared when walking the tree. That results > in different pointers being returned later and page permission violation > errors panicking the kernel. > > Reset tag of the address range inserted into the maple tree inside > execmem_vmalloc() which then gets propagated to execmem_cache_add(). > > Signed-off-by: Maciej Wieczor-Retman Acked-by: Alexander Potapenko > diff --git a/mm/execmem.c b/mm/execmem.c > index 810a4ba9c924..fd11409a6217 100644 > --- a/mm/execmem.c > +++ b/mm/execmem.c > @@ -59,7 +59,7 @@ static void *execmem_vmalloc(struct execmem_range *rang= e, size_t size, > return NULL; > } > > - return p; > + return kasan_reset_tag(p); I think a comment would be nice here. > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3328,7 +3328,7 @@ static void vm_reset_perms(struct vm_struct *area) > * the vm_unmap_aliases() flush includes the direct map. > */ > for (i =3D 0; i < area->nr_pages; i +=3D 1U << page_order) { > - unsigned long addr =3D (unsigned long)page_address(area->= pages[i]); > + unsigned long addr =3D (unsigned long)kasan_reset_tag(pag= e_address(area->pages[i])); Ditto