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: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tony 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>

8 files changed, 8 insertions, 8 deletions

diff --git a/arch/ia64/include/asm/compat.h b/arch/ia64/include/asm/compat.h
index f90edc8..9301a28 100644
--- a/arch/ia64/include/asm/compat.h
+++ b/arch/ia64/include/asm/compat.h
@@ -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);
diff --git a/arch/mips/include/asm/compat.h b/arch/mips/include/asm/compat.h
index 613f691..dbc5106 100644
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -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;
diff --git a/arch/parisc/include/asm/compat.h b/arch/parisc/include/asm/compat.h
index 02b77ba..efa0b60c 100644
--- a/arch/parisc/include/asm/compat.h
+++ b/arch/parisc/include/asm/compat.h
@@ -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];
diff --git a/arch/powerpc/include/asm/compat.h b/arch/powerpc/include/asm/compat.h
index 396d21a..a11d4ea 100644
--- a/arch/powerpc/include/asm/compat.h
+++ b/arch/powerpc/include/asm/compat.h
@@ -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];
diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index 104f200..a875c2f 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -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;
 
diff --git a/arch/sparc/include/asm/compat.h b/arch/sparc/include/asm/compat.h
index 5016f76..6f57325 100644
--- a/arch/sparc/include/asm/compat.h
+++ b/arch/sparc/include/asm/compat.h
@@ -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];
diff --git a/arch/tile/include/asm/compat.h b/arch/tile/include/asm/compat.h
index 5a34da6..345d81c 100644
--- a/arch/tile/include/asm/compat.h
+++ b/arch/tile/include/asm/compat.h
@@ -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;
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 306160e..1d9cd27 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -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;