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Date: Wed, 16 Feb 2022 14:13:15 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Christoph Hellwig <hch@....de>, linux-arch@...r.kernel.org,
linux-mm@...ck.org, linux-api@...r.kernel.org, arnd@...db.de,
linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk
Cc: linux@...linux.org.uk, will@...nel.org, guoren@...nel.org,
bcain@...eaurora.org, geert@...ux-m68k.org, monstr@...str.eu,
tsbogend@...ha.franken.de, nickhu@...estech.com,
green.hu@...il.com, dinguyen@...nel.org, shorne@...il.com,
deller@....de, mpe@...erman.id.au, peterz@...radead.org,
mingo@...hat.com, mark.rutland@....com, hca@...ux.ibm.com,
dalias@...c.org, davem@...emloft.net, richard@....at,
x86@...nel.org, jcmvbkbc@...il.com, ebiederm@...ssion.com,
akpm@...ux-foundation.org, ardb@...nel.org,
linux-alpha@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
linux-csky@...r.kernel.org, linux-hexagon@...r.kernel.org,
linux-ia64@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
linux-mips@...r.kernel.org, openrisc@...ts.librecores.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org,
stable@...r.kernel.org, David Laight <David.Laight@...lab.com>
Subject: [PATCH v2 01/18] uaccess: fix integer overflow on access_ok()
From: Arnd Bergmann <arnd@...db.de>
Three architectures check the end of a user access against the
address limit without taking a possible overflow into account.
Passing a negative length or another overflow in here returns
success when it should not.
Use the most common correct implementation here, which optimizes
for a constant 'size' argument, and turns the common case into a
single comparison.
Cc: stable@...r.kernel.org
Fixes: da551281947c ("csky: User access")
Fixes: f663b60f5215 ("microblaze: Fix uaccess_ok macro")
Fixes: 7567746e1c0d ("Hexagon: Add user access functions")
Reported-by: David Laight <David.Laight@...lab.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
arch/csky/include/asm/uaccess.h | 7 +++----
arch/hexagon/include/asm/uaccess.h | 18 +++++++++---------
arch/microblaze/include/asm/uaccess.h | 19 ++++---------------
3 files changed, 16 insertions(+), 28 deletions(-)
diff --git a/arch/csky/include/asm/uaccess.h b/arch/csky/include/asm/uaccess.h
index c40f06ee8d3e..ac5a54f57d40 100644
--- a/arch/csky/include/asm/uaccess.h
+++ b/arch/csky/include/asm/uaccess.h
@@ -3,14 +3,13 @@
#ifndef __ASM_CSKY_UACCESS_H
#define __ASM_CSKY_UACCESS_H
-#define user_addr_max() \
- (uaccess_kernel() ? KERNEL_DS.seg : get_fs().seg)
+#define user_addr_max() (current_thread_info()->addr_limit.seg)
static inline int __access_ok(unsigned long addr, unsigned long size)
{
- unsigned long limit = current_thread_info()->addr_limit.seg;
+ unsigned long limit = user_addr_max();
- return ((addr < limit) && ((addr + size) < limit));
+ return (size <= limit) && (addr <= (limit - size));
}
#define __access_ok __access_ok
diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
index ef5bfef8d490..719ba3f3c45c 100644
--- a/arch/hexagon/include/asm/uaccess.h
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -25,17 +25,17 @@
* Returns true (nonzero) if the memory block *may* be valid, false (zero)
* if it is definitely invalid.
*
- * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
- * simple MSB-based tests used by MIPS won't work. Some further
- * optimization is probably possible here, but for now, keep it
- * reasonably simple and not *too* slow. After all, we've got the
- * MMU for backup.
*/
+#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
-#define __access_ok(addr, size) \
- ((get_fs().seg == KERNEL_DS.seg) || \
- (((unsigned long)addr < get_fs().seg) && \
- (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
+static inline int __access_ok(unsigned long addr, unsigned long size)
+{
+ unsigned long limit = TASK_SIZE;
+
+ return (size <= limit) && (addr <= (limit - size));
+}
+#define __access_ok __access_ok
/*
* When a kernel-mode page fault is taken, the faulting instruction
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index d2a8ef9f8978..5b6e0e7788f4 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -39,24 +39,13 @@
# define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-static inline int access_ok(const void __user *addr, unsigned long size)
+static inline int __access_ok(unsigned long addr, unsigned long size)
{
- if (!size)
- goto ok;
+ unsigned long limit = user_addr_max();
- if ((get_fs().seg < ((unsigned long)addr)) ||
- (get_fs().seg < ((unsigned long)addr + size - 1))) {
- pr_devel("ACCESS fail at 0x%08x (size 0x%x), seg 0x%08x\n",
- (__force u32)addr, (u32)size,
- (u32)get_fs().seg);
- return 0;
- }
-ok:
- pr_devel("ACCESS OK at 0x%08x (size 0x%x), seg 0x%08x\n",
- (__force u32)addr, (u32)size,
- (u32)get_fs().seg);
- return 1;
+ return (size <= limit) && (addr <= (limit - size));
}
+#define access_ok(addr, size) __access_ok((unsigned long)addr, size)
# define __FIXUP_SECTION ".section .fixup,\"ax\"\n"
# define __EX_TABLE_SECTION ".section __ex_table,\"a\"\n"
--
2.29.2
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