diff options
author | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-07 16:16:18 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-20 13:17:57 -0700 |
commit | 337b16213b3810a982e34f4b9497745c700da8a0 (patch) | |
tree | c411754cab0e44622d6226a9712799029fe9a079 /kernel/compat.c | |
parent | 7764ec137f93bb83dd287d14ad457325072aa00d (diff) |
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 <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/compat.c')
-rw-r--r-- | kernel/compat.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/compat.c b/kernel/compat.c index 180d1885f782..8bc557869d90 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -25,6 +25,7 @@ #include <linux/posix-timers.h> #include <linux/times.h> #include <linux/ptrace.h> +#include <linux/module.h> #include <asm/uaccess.h> @@ -1136,3 +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); |