linux-kernel - [PATCH v1 06/15] powerpc/uaccess: Call might

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <f26059443f3ded51abfe0a5c982b17b5d49341cf.1614275314.git.christophe.leroy@csgroup.eu>
Date:   Thu, 25 Feb 2021 17:50:36 +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 v1 06/15] powerpc/uaccess: Call might_fault() inconditionaly

Commit 6bfd93c32a50 ("powerpc: Fix incorrect might_sleep in
__get_user/__put_user on kernel addresses") added a check to not call
might_sleep() on kernel addresses. This was to enable the use of
__get_user() in the alignment exception handler for any address.

Then commit 95156f0051cb ("lockdep, mm: fix might_fault() annotation")
added a check of the address space in might_fault(), based on
set_fs() logic. But this didn't solve the powerpc alignment exception
case as it didn't call set_fs(KERNEL_DS).

Nowadays, set_fs() is gone, previous patch fixed the alignment
exception handler and __get_user/__put_user are not supposed to be
used anymore to read kernel memory.

Therefore the is_kernel_addr() check has become useless and can be
removed.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/uaccess.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index eaa828a6a419..c4bbc64758a0 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -77,8 +77,7 @@ __pu_failed:							\
 	__typeof__(*(ptr)) __pu_val = (x);			\
 	__typeof__(size) __pu_size = (size);			\
 								\
-	if (!is_kernel_addr((unsigned long)__pu_addr))		\
-		might_fault();					\
+	might_fault();						\
 	__chk_user_ptr(__pu_addr);				\
 	__put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err);	\
 								\
@@ -238,12 +237,12 @@ do {								\
 	__typeof__(size) __gu_size = (size);			\
 								\
 	__chk_user_ptr(__gu_addr);				\
-	if (do_allow && !is_kernel_addr((unsigned long)__gu_addr)) \
+	if (do_allow) {								\
 		might_fault();					\
-	if (do_allow)								\
 		__get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err);	\
-	else									\
+	} else {									\
 		__get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
+	}									\
 	(x) = (__typeof__(*(ptr)))__gu_val;			\
 								\
 	__gu_err;						\
-- 
2.25.0