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AJvYcCWlL0pJylL29CxE8Ye/brQB/qd/vu00b1nHJiTMEMmuPLqPWBZlkOvqOGUJbThg0dxiIfwDy09kuRA=@vger.kernel.org X-Gm-Message-State: AOJu0YzGCXQv+GqHjSV25Z1JeKEqtTPlaeaY+ogiqjeYoGoiduZMuO7S 0vOitI/1rw6HaJSZSqWVZlN0q+jloQkGc9ybo8ydlchp4tTGsi54IHcSoSeOknBkEobbeYu663D tlro/l0V8NAH8HHRRO6iRLq6aaeYbsF324emvlGlq X-Gm-Gg: ASbGncu/H6lit3rgc3bSy3azBgVdWbYCr2fm8vGum0GMzOaX+A7ig22hTb3rshhQRas CG0hjTJmZ3HO+lrXy3f1tZEGbJAkv6R/3yUkZHEUqceIkWUH4fdW3ViRLY3oGJD+E/Q/gevLIGm xjrAO4dsKpEBIm1CUvrLRjc6BP9mNbKUdkC0ddRVNa3f8GfAOJ2EJ6LkKB76sGSGXAGwyLdHsCA tenjeVOAZuPdfeYQcZeSJIVzYOnqtSy1cOSV+iufYv8AsZ0f1hZ/DRlZIpA6gpX+DvcYsA9OImr g8H+u7RrBnHEu0MwFsSGcKnP+p4ig487rGKh 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) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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