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[198.145.29.99]) by mx.google.com with ESMTPS id a15-v6si14003317pll.412.2018.05.20.23.43.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 20 May 2018 23:43:19 -0700 (PDT) Received-SPF: pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=0g68E+78; spf=pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=nia/=II=linuxfoundation.org=gregkh@kernel.org Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AB8FF2086A; Mon, 21 May 2018 06:43:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1526884999; bh=On61SM9AQM4cLBE5GO5CTrqjtAK8QLNpprcMIRCIaYc=; h=Subject:To:Cc:From:Date:From; b=0g68E+78sfnwGT1i+PV4JLfva29luju6AXKSqYXStIHAajgkFDFtawJwpN5kaRF7B ZqWg4AO0r/5CT7N1UG1y+mCnZj6LqiCqk0g7PavPJODm6wYMUk+4FBTjLxNOE9p8l+ UHXWFOdQf01pJQvbBM2gq0vL5idRHK5PFFinll1Q= Subject: Patch "x86/pkeys: Override pkey when moving away from PROT_EXEC" has been added to the 4.16-stable tree To: 20180509171351.084C5A71@viggo.jf.intel.com, akpm@linux-foundation.org, dave.hansen@intel.com, dave.hansen@linux.intel.com, gregkh@linuxfoundation.org, linux-mm@kvack.org, linuxram@us.ibm.com, mingo@kernel.org, mpe@ellerman.id.au, peterz@infradead.org, shakeelb@google.com, shuah@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: From: Date: Mon, 21 May 2018 08:41:52 +0200 Message-ID: <1526884912142213@kroah.com> MIME-Version: 1.0 X-stable: commit 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: X-Virus-Scanned: ClamAV using ClamSMTP This is a note to let you know that I've just added the patch titled x86/pkeys: Override pkey when moving away from PROT_EXEC to the 4.16-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-pkeys-override-pkey-when-moving-away-from-prot_exec.patch and it can be found in the queue-4.16 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. From 0a0b152083cfc44ec1bb599b57b7aab41327f998 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Wed, 9 May 2018 10:13:51 -0700 Subject: x86/pkeys: Override pkey when moving away from PROT_EXEC From: Dave Hansen commit 0a0b152083cfc44ec1bb599b57b7aab41327f998 upstream. I got a bug report that the following code (roughly) was causing a SIGSEGV: mprotect(ptr, size, PROT_EXEC); mprotect(ptr, size, PROT_NONE); mprotect(ptr, size, PROT_READ); *ptr = 100; The problem is hit when the mprotect(PROT_EXEC) is implicitly assigned a protection key to the VMA, and made that key ACCESS_DENY|WRITE_DENY. The PROT_NONE mprotect() failed to remove the protection key, and the PROT_NONE-> PROT_READ left the PTE usable, but the pkey still in place and left the memory inaccessible. To fix this, we ensure that we always "override" the pkee at mprotect() if the VMA does not have execute-only permissions, but the VMA has the execute-only pkey. We had a check for PROT_READ/WRITE, but it did not work for PROT_NONE. This entirely removes the PROT_* checks, which ensures that PROT_NONE now works. Reported-by: Shakeel Butt Signed-off-by: Dave Hansen Cc: Andrew Morton Cc: Dave Hansen Cc: Linus Torvalds Cc: Michael Ellermen Cc: Peter Zijlstra Cc: Ram Pai Cc: Shuah Khan Cc: Thomas Gleixner Cc: linux-mm@kvack.org Cc: stable@vger.kernel.org Fixes: 62b5f7d013f ("mm/core, x86/mm/pkeys: Add execute-only protection keys support") Link: http://lkml.kernel.org/r/20180509171351.084C5A71@viggo.jf.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/pkeys.h | 12 +++++++++++- arch/x86/mm/pkeys.c | 21 +++++++++++---------- 2 files changed, 22 insertions(+), 11 deletions(-) Patches currently in stable-queue which might be from dave.hansen@linux.intel.com are queue-4.16/x86-pkeys-override-pkey-when-moving-away-from-prot_exec.patch queue-4.16/x86-pkeys-do-not-special-case-protection-key-0.patch --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -2,6 +2,8 @@ #ifndef _ASM_X86_PKEYS_H #define _ASM_X86_PKEYS_H +#define ARCH_DEFAULT_PKEY 0 + #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1) extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, @@ -15,7 +17,7 @@ extern int __execute_only_pkey(struct mm static inline int execute_only_pkey(struct mm_struct *mm) { if (!boot_cpu_has(X86_FEATURE_OSPKE)) - return 0; + return ARCH_DEFAULT_PKEY; return __execute_only_pkey(mm); } @@ -56,6 +58,14 @@ bool mm_pkey_is_allocated(struct mm_stru return false; if (pkey >= arch_max_pkey()) return false; + /* + * The exec-only pkey is set in the allocation map, but + * is not available to any of the user interfaces like + * mprotect_pkey(). + */ + if (pkey == mm->context.execute_only_pkey) + return false; + return mm_pkey_allocation_map(mm) & (1U << pkey); } --- a/arch/x86/mm/pkeys.c +++ b/arch/x86/mm/pkeys.c @@ -94,26 +94,27 @@ int __arch_override_mprotect_pkey(struct */ if (pkey != -1) return pkey; - /* - * Look for a protection-key-drive execute-only mapping - * which is now being given permissions that are not - * execute-only. Move it back to the default pkey. - */ - if (vma_is_pkey_exec_only(vma) && - (prot & (PROT_READ|PROT_WRITE))) { - return 0; - } + /* * The mapping is execute-only. Go try to get the * execute-only protection key. If we fail to do that, * fall through as if we do not have execute-only - * support. + * support in this mm. */ if (prot == PROT_EXEC) { pkey = execute_only_pkey(vma->vm_mm); if (pkey > 0) return pkey; + } else if (vma_is_pkey_exec_only(vma)) { + /* + * Protections are *not* PROT_EXEC, but the mapping + * is using the exec-only pkey. This mapping was + * PROT_EXEC and will no longer be. Move back to + * the default pkey. + */ + return ARCH_DEFAULT_PKEY; } + /* * This is a vanilla, non-pkey mprotect (or we failed to * setup execute-only), inherit the pkey from the VMA we