linux-kernel - Re: [RFC][PATCH] x86: Verify access

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Message-ID: <f84a1055-f65b-fcd8-c914-46b328acd172@redhat.com>
Date:   Mon, 16 Jan 2017 14:27:55 -0600
From:   David Smith <dsmith@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Frank Ch. Eigler" <fche@...hat.com>
Subject: Re: [RFC][PATCH] x86: Verify access_ok() context

If you call access_ok() with page faulting disabled, you'll still see this new warning. If you put that new access_ok() call in a module that gets loaded/unloaded, you see one warning for every module load, which gets a bit annoying.

How about modifying it like this:

---
From: David Smith <dsmith@...hat.com>
Date: Mon, 16 Jan 2017 14:07:31 -0600
Subject: [PATCH] Relax x86 new access_ok() warning a bit.

Signed-off-by: David Smith <dsmith@...hat.com>
---
 arch/x86/include/asm/uaccess.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index ea148313570f..0cbd3cca5e7b 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -69,7 +69,7 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
 })
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
-# define WARN_ON_IN_IRQ()	WARN_ON_ONCE(!in_task())
+# define WARN_ON_IN_IRQ()	WARN_ON_ONCE(!in_task() && !pagefault_disabled())
 #else
 # define WARN_ON_IN_IRQ()
 #endif
-- 


-- 
David Smith
dsmith@...hat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)