linux-kernel - [PATCH x86/mm] x86: i387 fpregs_set convert_to

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Message-Id: <20080125015933.587DF26F9FD@magilla.localdomain>
Date:	Thu, 24 Jan 2008 17:59:33 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	mingo@...e.hu, tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH x86/mm] x86: i387 fpregs_set convert_to_fxsr

Thanks for catching that, Suresh.  
The fix needed a few nits different from your patch.


Thanks,
Roland

---

This fixes the bug introduced recently during the revamp of the code.
fpregs_set() needs to use convert_to_fxsr() rather than copying into the
fxsave struct directly.

Reported-by: Suresh Siddha <suresh.b.siddha@...el.com>
Signed-off-by: Roland McGrath <roland@...hat.com>
---
 arch/x86/kernel/i387.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 7e354a3..26719bd 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -326,6 +326,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 	       unsigned int pos, unsigned int count,
 	       const void *kbuf, const void __user *ubuf)
 {
+	struct user_i387_ia32_struct env;
 	int ret;
 
 	if (!HAVE_HWFP)
@@ -338,13 +339,12 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 		return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 					  &target->thread.i387.fsave, 0, -1);
 
-	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-				 &target->thread.i387.fxsave, 0, -1);
+	if (pos > 0 || count < sizeof(env))
+		convert_from_fxsr(&env, target);
 
-	/*
-	 * mxcsr reserved bits must be masked to zero for security reasons.
-	 */
-	target->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
+	if (!ret)
+		convert_to_fxsr(target, &env);
 
 	return ret;
 }
--
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