linux-kernel - [PATCH v3 1/3] syscalls: use uaccess_kernel in addr_limit_user

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Message-Id: <a6e62627d25fb7ae9b91d8bf553e707689e37498.1596702117.git.christophe.leroy@csgroup.eu>
Date:   Thu,  6 Aug 2020 08:23:08 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 1/3] syscalls: use uaccess_kernel in addr_limit_user_check

From: Christoph Hellwig <hch@....de>

Patch series "clean up address limit helpers", v2.

In preparation for eventually phasing out direct use of set_fs(), this
series removes the segment_eq() arch helper that is only used to implement
or duplicate the uaccess_kernel() API, and then adds descriptive helpers
to force the kernel address limit.

This patch (of 6):

Use the uaccess_kernel helper instead of duplicating it.

Link: http://lkml.kernel.org/r/20200714105505.935079-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200710135706.537715-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200710135706.537715-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@....de>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Nick Hu <nickhu@...estech.com>
Cc: Greentime Hu <green.hu@...il.com>
Cc: Vincent Chen <deanbo422@...il.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>
Cc: Palmer Dabbelt <palmer@...belt.com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
---
 include/linux/syscalls.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b951a87da987..e933a43d4a69 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -263,7 +263,7 @@ static inline void addr_limit_user_check(void)
 		return;
 #endif
 
-	if (CHECK_DATA_CORRUPTION(!segment_eq(get_fs(), USER_DS),
+	if (CHECK_DATA_CORRUPTION(uaccess_kernel(),
 				  "Invalid address limit on user-mode return"))
 		force_sig(SIGKILL);
 
-- 
2.25.0