Commit c41d68a5 authored by H. Peter Anvin's avatar H. Peter Anvin

compat: Make compat_alloc_user_space() incorporate the access_ok()

compat_alloc_user_space() expects the caller to independently call
access_ok() to verify the returned area.  A missing call could
introduce problems on some architectures.

This patch incorporates the access_ok() check into
compat_alloc_user_space() and also adds a sanity check on the length.
The existing compat_alloc_user_space() implementations are renamed
arch_compat_alloc_user_space() and are used as part of the
implementation of the new global function.

This patch assumes NULL will cause __get_user()/__put_user() to either
fail or access userspace on all architectures.  This should be
followed by checking the return value of compat_access_user_space()
for NULL in the callers, at which time the access_ok() in the callers
can also be removed.
Reported-by: default avatarBen Hawkes <hawkes@sota.gen.nz>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: default avatarChris Metcalf <cmetcalf@tilera.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarTony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@kernel.org>
parent bfa88ea7
......@@ -199,7 +199,7 @@ ptr_to_compat(void __user *uptr)
}
static __inline__ void __user *
compat_alloc_user_space (long len)
arch_compat_alloc_user_space (long len)
{
struct pt_regs *regs = task_pt_regs(current);
return (void __user *) (((regs->r12 & 0xffffffff) & -16) - len);
......
......@@ -145,7 +145,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = (struct pt_regs *)
((unsigned long) current_thread_info() + THREAD_SIZE - 32) - 1;
......
......@@ -147,7 +147,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
static __inline__ void __user *compat_alloc_user_space(long len)
static __inline__ void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = &current->thread.regs;
return (void __user *)regs->gr[30];
......
......@@ -134,7 +134,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = current->thread.regs;
unsigned long usp = regs->gpr[1];
......
......@@ -181,7 +181,7 @@ static inline int is_compat_task(void)
#endif
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
unsigned long stack;
......
......@@ -167,7 +167,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = current_thread_info()->kregs;
unsigned long usp = regs->u_regs[UREG_I6];
......
......@@ -195,7 +195,7 @@ static inline unsigned long ptr_to_compat_reg(void __user *uptr)
return (long)(int)(long __force)uptr;
}
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = task_pt_regs(current);
return (void __user *)regs->sp - len;
......
......@@ -205,7 +205,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
static inline void __user *compat_alloc_user_space(long len)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = task_pt_regs(current);
return (void __user *)regs->sp - len;
......
......@@ -360,5 +360,8 @@ extern ssize_t compat_rw_copy_check_uvector(int type,
const struct compat_iovec __user *uvector, unsigned long nr_segs,
unsigned long fast_segs, struct iovec *fast_pointer,
struct iovec **ret_pointer);
extern void __user *compat_alloc_user_space(unsigned long len);
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */
......@@ -1126,3 +1126,24 @@ compat_sys_sysinfo(struct compat_sysinfo __user *info)
return 0;
}
/*
* Allocate user-space memory for the duration of a single system call,
* in order to marshall parameters inside a compat thunk.
*/
void __user *compat_alloc_user_space(unsigned long len)
{
void __user *ptr;
/* If len would occupy more than half of the entire compat space... */
if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
return NULL;
ptr = arch_compat_alloc_user_space(len);
if (unlikely(!access_ok(VERIFY_WRITE, ptr, len)))
return NULL;
return ptr;
}
EXPORT_SYMBOL_GPL(compat_alloc_user_space);
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