From: Arnd Bergmann arnd@arndb.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@vger.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@aculab.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Arnd Bergmann arnd@arndb.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"