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sh: Fixup __strnlen_user() behaviour. 

Drop TIF_USERSPACE and add addr_limit to the thread_info struct.
Subsequently, use that for address checking in strnlen_user() to
ward off bogus -EFAULTs.

Make __strnlen_user() return 0 on exception, rather than -EFAULT.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2006-09-27 17:07:07 +09:00
parent 0f08f33808
commit 2991be7252
4 changed files with 22 additions and 54 deletions
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3
arch/sh/kernel/process.c
View File

@ -263,6 +263,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
unsigned long unused,
struct task_struct *p, struct pt_regs *regs)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs;
#if defined(CONFIG_SH_FPU)
struct task_struct *tsk = current;
@ -277,8 +278,10 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
if (user_mode(regs)) {
childregs->regs[15] = usp;
ti->addr_limit = USER_DS;
} else {
childregs->regs[15] = (unsigned long)task_stack_page(p) + THREAD_SIZE;
ti->addr_limit = KERNEL_DS;
}
if (clone_flags & CLONE_SETTLS) {
childregs->gbr = childregs->regs[0];

4
include/asm-sh/processor.h
View File

@ -149,6 +149,10 @@ struct thread_struct {
union sh_fpu_union fpu;
};
typedef struct {
unsigned long seg;
} mm_segment_t;
/* Count of active tasks with UBC settings */
extern int ubc_usercnt;

4
include/asm-sh/thread_info.h
View File

@ -21,6 +21,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
__u32 cpu;
int preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
@ -40,6 +41,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@ -95,7 +97,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 18
#define TIF_USERSPACE 31 /* true if FS sets userspace */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@ -103,7 +104,6 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_USERSPACE (1<<TIF_USERSPACE)
#define _TIF_WORK_MASK 0x000000FE /* work to do on interrupt/exception return */
#define _TIF_ALLWORK_MASK 0x000000FF /* work to do on any return to u-space */

65
include/asm-sh/uaccess.h
View File

@ -16,21 +16,9 @@
#include <linux/errno.h>
#include <linux/sched.h>
/*
* NOTE: Macro/functions in this file depends on threads_info.h implementation.
* Assumes:
* TI_FLAGS == 8
* TIF_USERSPACE == 31
* USER_ADDR_LIMIT == 0x80000000
*/
#define VERIFY_READ 0
#define VERIFY_WRITE 1
typedef struct {
unsigned int is_user_space;
} mm_segment_t;
/*
* The fs value determines whether argument validity checking should be
* performed or not. If get_fs() == USER_DS, checking is performed, with
@ -40,12 +28,14 @@ typedef struct {
*/
#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
#define segment_eq(a,b) ((a).is_user_space == (b).is_user_space)
#define USER_ADDR_LIMIT 0x80000000
#define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFFUL)
#define USER_DS MAKE_MM_SEG(PAGE_OFFSET)
#define KERNEL_DS MAKE_MM_SEG(0)
#define USER_DS MAKE_MM_SEG(1)
#define segment_eq(a,b) ((a).seg == (b).seg)
#define __addr_ok(addr) \
((unsigned long)(addr) < (current_thread_info()->addr_limit.seg))
#define get_ds() (KERNEL_DS)
@ -76,31 +66,8 @@ static inline int __access_ok(unsigned long addr, unsigned long size)
return ((addr >= memory_start) && ((addr + size) < memory_end));
}
#else /* CONFIG_MMU */
static inline mm_segment_t get_fs(void)
{
return MAKE_MM_SEG(test_thread_flag(TIF_USERSPACE));
}
static inline void set_fs(mm_segment_t s)
{
unsigned long ti, flag;
__asm__ __volatile__(
"stc r7_bank, %0\n\t"
"mov.l @(8,%0), %1\n\t"
"shal %1\n\t"
"cmp/pl %2\n\t"
"rotcr %1\n\t"
"mov.l %1, @(8,%0)"
: "=&r" (ti), "=&r" (flag)
: "r" (s.is_user_space)
: "t");
/****
if (s.is_user_space)
set_thread_flag(TIF_USERSPACE);
else
clear_thread_flag(TIF_USERSPACE);
****/
}
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
/*
* __access_ok: Check if address with size is OK or not.
@ -108,7 +75,7 @@ static inline void set_fs(mm_segment_t s)
* We do three checks:
* (1) is it user space?
* (2) addr + size --> carry?
* (3) addr + size >= 0x80000000 (USER_ADDR_LIMIT)
* (3) addr + size >= 0x80000000 (PAGE_OFFSET)
*
* (1) (2) (3) | RESULT
* 0 0 0 | ok
@ -541,7 +508,7 @@ static __inline__ long __strnlen_user(const char __user *__s, long __n)
"3:\n\t"
"mov.l 4f, %1\n\t"
"jmp @%1\n\t"
" mov %5, %0\n"
" mov #0, %0\n"
".balign 4\n"
"4: .long 2b\n"
".previous\n"
@ -550,26 +517,20 @@ static __inline__ long __strnlen_user(const char __user *__s, long __n)
" .long 1b,3b\n"
".previous"
: "=z" (res), "=&r" (__dummy)
: "0" (0), "r" (__s), "r" (__n), "i" (-EFAULT)
: "0" (0), "r" (__s), "r" (__n)
: "t");
return res;
}
static __inline__ long strnlen_user(const char __user *s, long n)
{
if (!access_ok(VERIFY_READ, s, n))
if (!__addr_ok(s))
return 0;
else
return __strnlen_user(s, n);
}
static __inline__ long strlen_user(const char __user *s)
{
if (!access_ok(VERIFY_READ, s, 0))
return 0;
else
return __strnlen_user(s, ~0UL >> 1);
}
#define strlen_user(str) strnlen_user(str, ~0UL >> 1)
/*
* The exception table consists of pairs of addresses: the first is the