linux-kernel - [PATCH 3/3] x86_64, copy_thread: Fix CLONE

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Message-Id: <45e2d0d695393d76406a0c7225b82c76223e0cc5.1424822291.git.luto@amacapital.net>
Date:	Tue, 24 Feb 2015 16:01:39 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Denys Vlasenko <dvlasenk@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...capital.net>
Subject: [PATCH 3/3] x86_64, copy_thread: Fix CLONE_SETTLS bitness

CLONE_SETTLS is expected to write a TLS entry in the GDT for 32-bit
callers and to set fsbase for 64-bit callers.

The correct check is is_ia32_task(), which returns true in the
context of a 32-bit syscall.  TIF_IA32 is set if the task itself has
a 32-bit personality, which is not the same thing.

Signed-off-by: Andy Lutomirski <luto@...capital.net>
---
 arch/x86/kernel/process_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 5a2c02913af3..936d43461dca 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -207,7 +207,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 	 */
 	if (clone_flags & CLONE_SETTLS) {
 #ifdef CONFIG_IA32_EMULATION
-		if (test_thread_flag(TIF_IA32))
+		if (is_ia32_task())
 			err = do_set_thread_area(p, -1,
 				(struct user_desc __user *)childregs->si, 0);
 		else
-- 
2.3.0

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