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Date: Sun, 2 Jan 2011 02:16:16 -0500
From: Paul Gortmaker <paul.gortmaker@...driver.com>
To: stable@...nel.org, linux-kernel@...r.kernel.org
Cc: stable-review@...nel.org, "H. Peter Anvin" <hpa@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Arnd Bergmann <arnd@...db.de>,
Fenghua Yu <fenghua.yu@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Helge Deller <deller@....de>,
James Bottomley <jejb@...isc-linux.org>,
Kyle McMartin <kyle@...artin.ca>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Paul Mackerras <paulus@...ba.org>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 080/260] compat: Make compat_alloc_user_space() incorporate the access_ok()
From: H. Peter Anvin <hpa@...ux.intel.com>
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 <hawkes@...a.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@...era.com>
Acked-by: David S. Miller <davem@...emloft.net>
Acked-by: Ingo Molnar <mingo@...e.hu>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Tony Luck <tony.luck@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Helge Deller <deller@....de>
Cc: James Bottomley <jejb@...isc-linux.org>
Cc: Kyle McMartin <kyle@...artin.ca>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
arch/ia64/include/asm/compat.h | 2 +-
arch/mips/include/asm/compat.h | 2 +-
arch/parisc/include/asm/compat.h | 2 +-
arch/powerpc/include/asm/compat.h | 2 +-
arch/s390/include/asm/compat.h | 2 +-
arch/sparc/include/asm/compat.h | 2 +-
arch/x86/include/asm/compat.h | 2 +-
include/linux/compat.h | 3 +++
kernel/compat.c | 21 +++++++++++++++++++++
9 files changed, 31 insertions(+), 7 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..efa0b60 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 = ¤t->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/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;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 168f7da..c766441 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -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 */
diff --git a/kernel/compat.c b/kernel/compat.c
index 5adab05..91b33fb 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -1137,3 +1137,24 @@ 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);
--
1.7.3.3
--
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