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uaccess: fix integer overflow on access_ok()

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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@vger.kernel.org
Fixes: da55128194 ("csky: User access")
Fixes: f663b60f52 ("microblaze: Fix uaccess_ok macro")
Fixes: 7567746e1c ("Hexagon: Add user access functions")
Reported-by: David Laight <David.Laight@aculab.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Arnd Bergmann
2022-02-10 16:24:30 +01:00
parent dfd42facf1
commit 222ca305c9
3 changed files with 16 additions and 28 deletions
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arch/microblaze/include/asm/uaccess.h
+4 -15
View File
@@ -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"