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[46.135.14.82]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4773c53eafbsm6728865e9.12.2025.10.31.10.42.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 10:42:32 -0700 (PDT) From: Mateusz Guzik To: torvalds@linux-foundation.org Cc: brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tglx@linutronix.de, pfalcato@suse.de, Mateusz Guzik Subject: [PATCH 1/3] x86: fix access_ok() and valid_user_address() using wrong USER_PTR_MAX in modules Date: Fri, 31 Oct 2025 18:42:18 +0100 Message-ID: <20251031174220.43458-2-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251031174220.43458-1-mjguzik@gmail.com> References: <20251031174220.43458-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" [real commit message will land here later] --- arch/x86/include/asm/uaccess_64.h | 17 +++++++++-------- arch/x86/kernel/cpu/common.c | 8 +++++--- 2 files changed, 14 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uacce= ss_64.h index c8a5ae35c871..f60c0ed147c3 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -12,13 +12,14 @@ #include #include #include -#include =20 -/* - * Virtual variable: there's no actual backing store for this, - * it can purely be used as 'runtime_const_ptr(USER_PTR_MAX)' - */ -extern unsigned long USER_PTR_MAX; +extern unsigned long user_ptr_max; +#ifdef MODULE +#define __user_ptr_max_accessor user_ptr_max +#else +#include +#define __user_ptr_max_accessor runtime_const_ptr(user_ptr_max) +#endif =20 #ifdef CONFIG_ADDRESS_MASKING /* @@ -54,7 +55,7 @@ static inline unsigned long __untagged_addr_remote(struct= mm_struct *mm, #endif =20 #define valid_user_address(x) \ - likely((__force unsigned long)(x) <=3D runtime_const_ptr(USER_PTR_MAX)) + likely((__force unsigned long)(x) <=3D __user_ptr_max_accessor) =20 /* * Masking the user address is an alternative to a conditional @@ -67,7 +68,7 @@ static inline void __user *mask_user_address(const void _= _user *ptr) asm("cmp %1,%0\n\t" "cmova %1,%0" :"=3Dr" (ret) - :"r" (runtime_const_ptr(USER_PTR_MAX)), + :"r" (__user_ptr_max_accessor), "0" (ptr)); return ret; } diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 3ff9682d8bc4..f338f5e9adfc 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -78,6 +78,9 @@ DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info); EXPORT_PER_CPU_SYMBOL(cpu_info); =20 +unsigned long user_ptr_max __ro_after_init; +EXPORT_SYMBOL(user_ptr_max); + u32 elf_hwcap2 __read_mostly; =20 /* Number of siblings per CPU package */ @@ -2575,14 +2578,13 @@ void __init arch_cpu_finalize_init(void) alternative_instructions(); =20 if (IS_ENABLED(CONFIG_X86_64)) { - unsigned long USER_PTR_MAX =3D TASK_SIZE_MAX; - + user_ptr_max =3D TASK_SIZE_MAX; /* * Enable this when LAM is gated on LASS support if (cpu_feature_enabled(X86_FEATURE_LAM)) USER_PTR_MAX =3D (1ul << 63) - PAGE_SIZE; */ - runtime_const_init(ptr, USER_PTR_MAX); + runtime_const_init(ptr, user_ptr_max); =20 /* * Make sure the first 2MB area is not mapped by huge pages --=20 2.34.1