From: Arnd Bergmann arnd@arndb.de
commit 26509034bef198525d5936c116cbd0c3fa491c0b upstream.
While most m68k platforms use separate address spaces for user and kernel space, at least coldfire does not, and the other ones have a TASK_SIZE that is less than the entire 4GB address range.
Using the default implementation of __access_ok() stops coldfire user space from trivially accessing kernel memory.
Reviewed-by: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/m68k/include/asm/uaccess.h | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
--- a/arch/m68k/include/asm/uaccess.h +++ b/arch/m68k/include/asm/uaccess.h @@ -12,14 +12,17 @@ #include <asm/extable.h>
/* We let the MMU do all checking */ -static inline int access_ok(const void __user *addr, +static inline int access_ok(const void __user *ptr, unsigned long size) { - /* - * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check - * for TASK_SIZE! - */ - return 1; + unsigned long limit = TASK_SIZE; + unsigned long addr = (unsigned long)ptr; + + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES) || + !IS_ENABLED(CONFIG_MMU)) + return 1; + + return (size <= limit) && (addr <= (limit - size)); }
/*