linux-kernel - [PATCH v5 20/23] x86/kprobes: Use vmalloc special flag

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Date:   Thu, 25 Apr 2019 17:11:40 -0700
From:   Nadav Amit <namit@...are.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>
CC:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nadav Amit <nadav.amit@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        <linux_dti@...oud.com>, <linux-integrity@...r.kernel.org>,
        <linux-security-module@...r.kernel.org>,
        <akpm@...ux-foundation.org>, <kernel-hardening@...ts.openwall.com>,
        <linux-mm@...ck.org>, <will.deacon@....com>,
        <ard.biesheuvel@...aro.org>, <kristen@...ux.intel.com>,
        <deneen.t.dock@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: [PATCH v5 20/23] x86/kprobes: Use vmalloc special flag

From: Rick Edgecombe <rick.p.edgecombe@...el.com>

Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set NX
and RW before freeing which is no longer needed.

Cc: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---
 arch/x86/kernel/kprobes/core.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 1591852d3ac4..136695e4434a 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -434,6 +434,7 @@ void *alloc_insn_page(void)
 	if (!page)
 		return NULL;
 
+	set_vm_flush_reset_perms(page);
 	/*
 	 * First make the page read-only, and only then make it executable to
 	 * prevent it from being W+X in between.
@@ -452,12 +453,6 @@ void *alloc_insn_page(void)
 /* Recover page to RW mode before releasing it */
 void free_insn_page(void *page)
 {
-	/*
-	 * First make the page non-executable, and only then make it writable to
-	 * prevent it from being W+X in between.
-	 */
-	set_memory_nx((unsigned long)page, 1);
-	set_memory_rw((unsigned long)page, 1);
 	module_memfree(page);
 }
 
-- 
2.17.1