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176 lines
6.1 KiB
176 lines
6.1 KiB
From: H. Peter Anvin <hpa@linux.intel.com>
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Date: Tue, 7 Sep 2010 23:16:18 +0000 (-0700)
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Subject: compat: Make compat_alloc_user_space() incorporate the access_ok()
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Git-commit: c41d68a513c71e35a14f66d71782d27a79a81ea6
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References: CVE-2010-3081 bnc#639709
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Patch-mainline: 2.6.36
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Introduced-by: Prior to 2.6.5
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compat: Make compat_alloc_user_space() incorporate the access_ok()
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compat_alloc_user_space() expects the caller to independently call
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access_ok() to verify the returned area. A missing call could
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introduce problems on some architectures.
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This patch incorporates the access_ok() check into
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compat_alloc_user_space() and also adds a sanity check on the length.
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The existing compat_alloc_user_space() implementations are renamed
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arch_compat_alloc_user_space() and are used as part of the
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implementation of the new global function.
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This patch assumes NULL will cause __get_user()/__put_user() to either
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fail or access userspace on all architectures. This should be
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followed by checking the return value of compat_access_user_space()
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for NULL in the callers, at which time the access_ok() in the callers
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can also be removed.
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Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
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Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Acked-by: Chris Metcalf <cmetcalf@tilera.com>
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Acked-by: David S. Miller <davem@davemloft.net>
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Acked-by: Ingo Molnar <mingo@elte.hu>
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Acked-by: Thomas Gleixner <tglx@linutronix.de>
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Acked-by: Tony Luck <tony.luck@intel.com>
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Cc: Andrew Morton <akpm@linux-foundation.org>
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Cc: Arnd Bergmann <arnd@arndb.de>
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Cc: Fenghua Yu <fenghua.yu@intel.com>
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
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Cc: Helge Deller <deller@gmx.de>
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Cc: James Bottomley <jejb@parisc-linux.org>
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Cc: Kyle McMartin <kyle@mcmartin.ca>
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Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Cc: Paul Mackerras <paulus@samba.org>
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Cc: Ralf Baechle <ralf@linux-mips.org>
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Cc: <stable@kernel.org>
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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arch/ia64/include/asm/compat.h | 2 +-
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arch/mips/include/asm/compat.h | 2 +-
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arch/parisc/include/asm/compat.h | 2 +-
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arch/powerpc/include/asm/compat.h | 2 +-
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arch/s390/include/asm/compat.h | 2 +-
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arch/sparc/include/asm/compat.h | 2 +-
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arch/x86/include/asm/compat.h | 2 +-
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include/linux/compat.h | 3 +++
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kernel/compat.c | 21 +++++++++++++++++++++
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9 files changed, 31 insertions(+), 7 deletions(-)
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--- a/arch/ia64/include/asm/compat.h
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+++ b/arch/ia64/include/asm/compat.h
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@@ -199,7 +199,7 @@ ptr_to_compat(void __user *uptr)
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}
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static __inline__ void __user *
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-compat_alloc_user_space (long len)
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+arch_compat_alloc_user_space (long len)
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{
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struct pt_regs *regs = task_pt_regs(current);
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return (void __user *) (((regs->r12 & 0xffffffff) & -16) - len);
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--- a/arch/mips/include/asm/compat.h
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+++ b/arch/mips/include/asm/compat.h
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@@ -145,7 +145,7 @@ static inline compat_uptr_t ptr_to_compa
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return (u32)(unsigned long)uptr;
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}
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-static inline void __user *compat_alloc_user_space(long len)
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+static inline void __user *arch_compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = (struct pt_regs *)
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((unsigned long) current_thread_info() + THREAD_SIZE - 32) - 1;
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--- a/arch/parisc/include/asm/compat.h
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+++ b/arch/parisc/include/asm/compat.h
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@@ -147,7 +147,7 @@ static inline compat_uptr_t ptr_to_compa
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return (u32)(unsigned long)uptr;
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}
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-static __inline__ void __user *compat_alloc_user_space(long len)
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+static __inline__ void __user *arch_compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = ¤t->thread.regs;
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return (void __user *)regs->gr[30];
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--- a/arch/powerpc/include/asm/compat.h
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+++ b/arch/powerpc/include/asm/compat.h
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@@ -134,7 +134,7 @@ static inline compat_uptr_t ptr_to_compa
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return (u32)(unsigned long)uptr;
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}
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-static inline void __user *compat_alloc_user_space(long len)
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+static inline void __user *arch_compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = current->thread.regs;
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unsigned long usp = regs->gpr[1];
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--- a/arch/s390/include/asm/compat.h
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+++ b/arch/s390/include/asm/compat.h
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@@ -181,7 +181,7 @@ static inline int is_compat_task(void)
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#endif
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-static inline void __user *compat_alloc_user_space(long len)
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+static inline void __user *arch_compat_alloc_user_space(long len)
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{
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unsigned long stack;
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--- a/arch/sparc/include/asm/compat.h
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+++ b/arch/sparc/include/asm/compat.h
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@@ -167,7 +167,7 @@ static inline compat_uptr_t ptr_to_compa
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return (u32)(unsigned long)uptr;
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}
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-static inline void __user *compat_alloc_user_space(long len)
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+static inline void __user *arch_compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = current_thread_info()->kregs;
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unsigned long usp = regs->u_regs[UREG_I6];
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--- a/arch/x86/include/asm/compat.h
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+++ b/arch/x86/include/asm/compat.h
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@@ -205,7 +205,7 @@ static inline compat_uptr_t ptr_to_compa
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return (u32)(unsigned long)uptr;
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}
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-static inline void __user *compat_alloc_user_space(long len)
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+static inline void __user *arch_compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = task_pt_regs(current);
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return (void __user *)regs->sp - len;
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--- a/include/linux/compat.h
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+++ b/include/linux/compat.h
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@@ -360,5 +360,8 @@ extern ssize_t compat_rw_copy_check_uvec
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const struct compat_iovec __user *uvector, unsigned long nr_segs,
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unsigned long fast_segs, struct iovec *fast_pointer,
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struct iovec **ret_pointer);
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+
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+extern void __user *compat_alloc_user_space(unsigned long len);
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+
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#endif /* CONFIG_COMPAT */
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#endif /* _LINUX_COMPAT_H */
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--- a/kernel/compat.c
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+++ b/kernel/compat.c
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@@ -1137,3 +1137,24 @@ compat_sys_sysinfo(struct compat_sysinfo
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return 0;
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}
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+
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+/*
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+ * Allocate user-space memory for the duration of a single system call,
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+ * in order to marshall parameters inside a compat thunk.
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+ */
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+void __user *compat_alloc_user_space(unsigned long len)
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+{
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+ void __user *ptr;
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+
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+ /* If len would occupy more than half of the entire compat space... */
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+ if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
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+ return NULL;
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+
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+ ptr = arch_compat_alloc_user_space(len);
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+
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+ if (unlikely(!access_ok(VERIFY_WRITE, ptr, len)))
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+ return NULL;
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+
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+ return ptr;
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+}
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+EXPORT_SYMBOL_GPL(compat_alloc_user_space);
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