linux-kernel - [tip:x86/smap] x86, smap: Handle csum_partial_copy_*

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Message-ID: <tip-2aps0u00eer658fd5xyanan7@git.kernel.org>
Date:	Sun, 1 Sep 2013 14:45:46 -0700
From:	"tip-bot for H. Peter Anvin" <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	tglx@...utronix.de, hpa@...ux.intel.com
Subject: [tip:x86/smap] x86, smap: Handle csum_partial_copy_*_user()

Commit-ID:  7263dda41b5a28ae6566fd126d9b06ada73dd721
Gitweb:     http://git.kernel.org/tip/7263dda41b5a28ae6566fd126d9b06ada73dd721
Author:     H. Peter Anvin <hpa@...ux.intel.com>
AuthorDate: Fri, 30 Aug 2013 15:43:03 -0700
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
CommitDate: Sun, 1 Sep 2013 14:09:48 -0700

x86, smap: Handle csum_partial_copy_*_user()

Add SMAP annotations to csum_partial_copy_to/from_user().  These
functions legitimately access user space and thus need to set the AC
flag.

TODO: add explicit checks that the side with the kernel space pointer
really points into kernel space.

Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Link: http://lkml.kernel.org/n/tip-2aps0u00eer658fd5xyanan7@git.kernel.org
Cc: <stable@...r.kernel.org> # v3.7+
---
 arch/x86/include/asm/checksum_32.h | 22 +++++++++++++++++-----
 arch/x86/lib/csum-wrappers_64.c    | 12 ++++++++++--
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/checksum_32.h b/arch/x86/include/asm/checksum_32.h
index 46fc474..f50de69 100644
--- a/arch/x86/include/asm/checksum_32.h
+++ b/arch/x86/include/asm/checksum_32.h
@@ -49,9 +49,15 @@ static inline __wsum csum_partial_copy_from_user(const void __user *src,
 						 int len, __wsum sum,
 						 int *err_ptr)
 {
+	__wsum ret;
+
 	might_sleep();
-	return csum_partial_copy_generic((__force void *)src, dst,
-					 len, sum, err_ptr, NULL);
+	stac();
+	ret = csum_partial_copy_generic((__force void *)src, dst,
+					len, sum, err_ptr, NULL);
+	clac();
+
+	return ret;
 }
 
 /*
@@ -176,10 +182,16 @@ static inline __wsum csum_and_copy_to_user(const void *src,
 					   int len, __wsum sum,
 					   int *err_ptr)
 {
+	__wsum ret;
+
 	might_sleep();
-	if (access_ok(VERIFY_WRITE, dst, len))
-		return csum_partial_copy_generic(src, (__force void *)dst,
-						 len, sum, NULL, err_ptr);
+	if (access_ok(VERIFY_WRITE, dst, len)) {
+		stac();
+		ret = csum_partial_copy_generic(src, (__force void *)dst,
+						len, sum, NULL, err_ptr);
+		clac();
+		return ret;
+	}
 
 	if (len)
 		*err_ptr = -EFAULT;
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index 25b7ae8..7609e0e 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -6,6 +6,7 @@
  */
 #include <asm/checksum.h>
 #include <linux/module.h>
+#include <asm/smap.h>
 
 /**
  * csum_partial_copy_from_user - Copy and checksum from user space.
@@ -52,8 +53,10 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 			len -= 2;
 		}
 	}
+	stac();
 	isum = csum_partial_copy_generic((__force const void *)src,
 				dst, len, isum, errp, NULL);
+	clac();
 	if (unlikely(*errp))
 		goto out_err;
 
@@ -82,6 +85,8 @@ __wsum
 csum_partial_copy_to_user(const void *src, void __user *dst,
 			  int len, __wsum isum, int *errp)
 {
+	__wsum ret;
+
 	might_sleep();
 
 	if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
@@ -105,8 +110,11 @@ csum_partial_copy_to_user(const void *src, void __user *dst,
 	}
 
 	*errp = 0;
-	return csum_partial_copy_generic(src, (void __force *)dst,
-					 len, isum, NULL, errp);
+	stac();
+	ret = csum_partial_copy_generic(src, (void __force *)dst,
+					len, isum, NULL, errp);
+	clac();
+	return ret;
 }
 EXPORT_SYMBOL(csum_partial_copy_to_user);
 
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