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Date: Sat, 18 Sep 2010 11:45:03 -0700 From: Greg KH <gregkh@...e.de> To: linux-kernel@...r.kernel.org, stable@...nel.org Cc: stable-review@...nel.org, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, "H. Peter Anvin" <hpa@...ux.intel.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Chris Metcalf <cmetcalf@...era.com>, "David S. Miller" <davem@...emloft.net>, Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, Tony Luck <tony.luck@...el.com>, 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> Subject: [07/11] compat: Make compat_alloc_user_space() incorporate the access_ok() 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ 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: Greg Kroah-Hartman <gregkh@...e.de> --- arch/ia64/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 +- include/asm-mips/compat.h | 2 +- include/asm-parisc/compat.h | 2 +- include/asm-x86/compat.h | 2 +- include/linux/compat.h | 2 ++ kernel/compat.c | 22 ++++++++++++++++++++++ 9 files changed, 31 insertions(+), 7 deletions(-) --- a/arch/ia64/include/asm/compat.h +++ b/arch/ia64/include/asm/compat.h @@ -198,7 +198,7 @@ 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); --- a/arch/powerpc/include/asm/compat.h +++ b/arch/powerpc/include/asm/compat.h @@ -133,7 +133,7 @@ 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]; --- a/arch/s390/include/asm/compat.h +++ b/arch/s390/include/asm/compat.h @@ -163,7 +163,7 @@ 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) { unsigned long stack; --- a/arch/sparc/include/asm/compat.h +++ b/arch/sparc/include/asm/compat.h @@ -166,7 +166,7 @@ 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]; --- a/include/asm-mips/compat.h +++ b/include/asm-mips/compat.h @@ -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; --- a/include/asm-parisc/compat.h +++ b/include/asm-parisc/compat.h @@ -146,7 +146,7 @@ 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]; --- a/include/asm-x86/compat.h +++ b/include/asm-x86/compat.h @@ -204,7 +204,7 @@ 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; --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -291,5 +291,7 @@ asmlinkage long compat_sys_newfstatat(un asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename, int flags, int mode); +extern void __user *compat_alloc_user_space(unsigned long len); + #endif /* CONFIG_COMPAT */ #endif /* _LINUX_COMPAT_H */ --- a/kernel/compat.c +++ b/kernel/compat.c @@ -23,6 +23,7 @@ #include <linux/timex.h> #include <linux/migrate.h> #include <linux/posix-timers.h> +#include <linux/module.h> #include <asm/uaccess.h> @@ -1081,3 +1082,24 @@ 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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