I pushed this patch upstream to Linus for 3.13-rc1: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=63379c135331c724d40a87b98eb62d2122981341 Now, after some more testing it seems this patch breaks userspace when booted with a 64bit kernel on machines >= 4GB RAM. All my machines with less than 4GB are OK. So, in case someone tries 3.13-rcX, please drop this patch if your machine has >= 4GB RAM... I still need to understand why it breaks and will follow up with a revert or a fix. Helge On 06/29/2013 02:03 PM, Helge Deller wrote: > Up to now PA-RISC could live with a trivial version of access_ok(). > Our fault handlers can correctly handle fault cases. > > But testcases showed that we need a better access check else we won't > always return correct errno failure codes to userspace. > > Problem showed up during 32bit userspace tests in which writev() used a > 32bit memory area and length which would then wrap around on 64bit > kernel. > > Signed-off-by: Helge Deller <deller@xxxxxx> > > diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h > index e0a8235..37ca987 100644 > --- a/arch/parisc/include/asm/uaccess.h > +++ b/arch/parisc/include/asm/uaccess.h > @@ -4,11 +4,14 @@ > /* > * User space memory access functions > */ > +#include <asm/processor.h> > #include <asm/page.h> > #include <asm/cache.h> > #include <asm/errno.h> > #include <asm-generic/uaccess-unaligned.h> > > +#include <linux/sched.h> > + > #define VERIFY_READ 0 > #define VERIFY_WRITE 1 > > @@ -33,12 +36,43 @@ extern int __get_user_bad(void); > extern int __put_kernel_bad(void); > extern int __put_user_bad(void); > > -static inline long access_ok(int type, const void __user * addr, > - unsigned long size) > + > +/* > + * Test whether a block of memory is a valid user space address. > + * Returns 0 if the range is valid, nonzero otherwise. > + */ > +static inline int __range_not_ok(unsigned long addr, unsigned long size, > + unsigned long limit) > { > - return 1; > + unsigned long __newaddr = addr + size; > + return (__newaddr < addr || __newaddr > limit || size > limit); > } > > +/** > + * access_ok: - Checks if a user space pointer is valid > + * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that > + * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe > + * to write to a block, it is always safe to read from it. > + * @addr: User space pointer to start of block to check > + * @size: Size of block to check > + * > + * Context: User context only. This function may sleep. > + * > + * Checks if a pointer to a block of memory in user space is valid. > + * > + * Returns true (nonzero) if the memory block may be valid, false (zero) > + * if it is definitely invalid. > + * > + * Note that, depending on architecture, this function probably just > + * checks that the pointer is in the user space range - after calling > + * this function, memory access functions may still return -EFAULT. > + */ > +#define access_ok(type, addr, size) \ > +( __chk_user_ptr(addr), \ > + !__range_not_ok((unsigned long) (__force void *) (addr), \ > + size, user_addr_max()) \ > +) > + > #define put_user __put_user > #define get_user __get_user > > @@ -218,7 +252,11 @@ extern long lstrnlen_user(const char __user *,long); > /* > * Complex access routines -- macros > */ > -#define user_addr_max() (~0UL) > +#ifdef CONFIG_COMPAT > +#define user_addr_max() (TASK_SIZE) > +#else > +#define user_addr_max() (DEFAULT_TASK_SIZE) > +#endif > > #define strnlen_user lstrnlen_user > #define strlen_user(str) lstrnlen_user(str, 0x7fffffffL) > -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
