Backported for 2.6.34.7 by Kerin Millar --- From: H. Peter Anvin 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 Signed-off-by: H. Peter Anvin Acked-by: Benjamin Herrenschmidt Acked-by: Chris Metcalf Acked-by: David S. Miller Acked-by: Ingo Molnar Acked-by: Thomas Gleixner Acked-by: Tony Luck Cc: Andrew Morton Cc: Arnd Bergmann Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Heiko Carstens Cc: Helge Deller Cc: James Bottomley Cc: Kyle McMartin Cc: Martin Schwidefsky Cc: Paul Mackerras Cc: Ralf Baechle Signed-off-by: Greg Kroah-Hartman --- 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 = ¤t->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 #include #include +#include #include #include @@ -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);