[patch] Backported patch for 2.6.34.7

2.6.34.7_compat_alloc_user_space-incorporate-access_ok.patch (text/plain), 7.77 KB, created by kfm on 2010-09-26 23:59:12 UTC

Backported for 2.6.34.7 by Kerin Millar <[e-mail]>
---

From: H. Peter Anvin <[e-mail]>
Date: Tue, 7 Sep 2010 23:16:18 +0000 (-0700)
Subject: compat: Make compat_alloc_user_space() incorporate the access_ok()
X-Git-Tag: v2.6.32.22~62
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fstable%2Flinux-2.6.32.y.git;a=commitdiff_plain;h=337b16213b3810a982e34f4b9497745c700da8a0

compat: Make compat_alloc_user_space() incorporate the access_ok()

commit c41d68a513c71e35a14f66d71782d27a79a81ea6 upstream.

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 <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>
Acked-by: Benjamin Herrenschmidt <[e-mail]>
Acked-by: Chris Metcalf <[e-mail]>
Acked-by: David S. Miller <[e-mail]>
Acked-by: Ingo Molnar <[e-mail]>
Acked-by: Thomas Gleixner <[e-mail]>
Acked-by: Tony Luck <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Fenghua Yu <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: James Bottomley <[e-mail]>
Cc: Kyle McMartin <[e-mail]>
Cc: Martin Schwidefsky <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
---

diff -urp linux-2.6.34.7.orig/arch/ia64/include/asm/compat.h linux-2.6.34.7/arch/ia64/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/ia64/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/ia64/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -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 -urp linux-2.6.34.7.orig/arch/mips/include/asm/compat.h linux-2.6.34.7/arch/mips/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/mips/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/mips/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -145,7 +145,7 @@ static inline compat_uptr_t ptr_to_compa
 	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 -urp linux-2.6.34.7.orig/arch/parisc/include/asm/compat.h linux-2.6.34.7/arch/parisc/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/parisc/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/parisc/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -147,7 +147,7 @@ static inline compat_uptr_t ptr_to_compa
 	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 -urp linux-2.6.34.7.orig/arch/powerpc/include/asm/compat.h linux-2.6.34.7/arch/powerpc/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/powerpc/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/powerpc/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -134,7 +134,7 @@ static inline compat_uptr_t ptr_to_compa
 	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 -urp linux-2.6.34.7.orig/arch/s390/include/asm/compat.h linux-2.6.34.7/arch/s390/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/s390/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/s390/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -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 -urp linux-2.6.34.7.orig/arch/sparc/include/asm/compat.h linux-2.6.34.7/arch/sparc/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/sparc/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/sparc/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -167,7 +167,7 @@ static inline compat_uptr_t ptr_to_compa
 	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 -urp linux-2.6.34.7.orig/arch/x86/include/asm/compat.h linux-2.6.34.7/arch/x86/include/asm/compat.h
--- linux-2.6.34.7.orig/arch/x86/include/asm/compat.h	2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34.7/arch/x86/include/asm/compat.h	2010-09-27 00:53:03.712604894 +0100
@@ -205,7 +205,7 @@ static inline compat_uptr_t ptr_to_compa
 	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;
diff -urp linux-2.6.34.7.orig/include/linux/compat.h linux-2.6.34.7/include/linux/compat.h
--- linux-2.6.34.7.orig/include/linux/compat.h	2010-09-26 23:12:10.377096155 +0100
+++ linux-2.6.34.7/include/linux/compat.h	2010-09-27 00:54:31.405104526 +0100
@@ -360,5 +360,8 @@ extern ssize_t compat_rw_copy_check_uvec
 		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 */
diff -urp linux-2.6.34.7.orig/kernel/compat.c linux-2.6.34.7/kernel/compat.c
--- linux-2.6.34.7.orig/kernel/compat.c	2010-09-26 23:12:10.381096260 +0100
+++ linux-2.6.34.7/kernel/compat.c	2010-09-27 00:55:28.401102437 +0100
@@ -25,6 +25,7 @@
 #include <linux/posix-timers.h>
 #include <linux/times.h>
 #include <linux/ptrace.h>
+#include <linux/module.h>
 #include <linux/gfp.h>
 
 #include <asm/uaccess.h>
@@ -1137,3 +1138,24 @@ compat_sys_sysinfo(struct compat_sysinfo
 
 	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);