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SubjectRe: [PATCH] Fix argument checking in sched_setaffinity

> I notice that you didn't bother with the fractional byte that is handled
> by 'endmask' in mm/mempolicy.c:get_nodes(). But I really don't give a
> hoot - either way is fine by me.
>
> I've written a couple of code snippets that manage to intuit the size of
> the kernel's cpumask dynamically from user space, by probing with
> various sched_getaffinity() calls. But since your patch only changes
> the errors generated by sched_setaffinity() [that's "set", not "get"], I
> will not experience any grief from this subtle change in the kernel's
> API.
>
> Should you lock hotplug before calling get_user_cpu_mask(), since
> get_user_cpu_mask() depends on cpu_online_mask()?

FYI the NUMA API and affinity code is broken on 64bit big endian. We
really need a get/set compat bitmap and use it. How does this look?
Not well tested yet...

Anton

diff -puN kernel/compat.c~compat_bitmap kernel/compat.c
--- gr_work/kernel/compat.c~compat_bitmap 2004-06-16 10:32:11.590272927 -0500
+++ gr_work-anton/kernel/compat.c 2004-06-16 10:32:11.607270238 -0500
@@ -561,3 +561,83 @@ long compat_clock_nanosleep(clockid_t wh

/* timer_create is architecture specific because it needs sigevent conversion */

+long compat_get_bitmap(unsigned long *mask, compat_ulong_t __user *umask,
+ unsigned long bitmap_size)
+{
+ int i, j;
+ unsigned long m;
+ compat_ulong_t um;
+ unsigned long nr_compat_longs;
+
+ /* align bitmap up to nearest compat_long_t boundary */
+ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
+
+ if (verify_area(VERIFY_READ, umask, bitmap_size / 8))
+ return -EFAULT;
+
+ nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
+
+ for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) {
+ m = 0;
+
+ for (j = 0; j < sizeof(m)/sizeof(um); j++) {
+ /*
+ * We dont want to read past the end of the userspace
+ * bitmap. We must however ensure the end of the
+ * kernel bitmap is zeroed.
+ */
+ if (nr_compat_longs-- > 0) {
+ if (__get_user(um, umask))
+ return -EFAULT;
+ } else {
+ um = 0;
+ }
+
+ umask++;
+ m |= (long)um << (j * BITS_PER_COMPAT_LONG);
+ }
+ *mask++ = m;
+ }
+
+ return 0;
+}
+
+long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
+ unsigned long bitmap_size)
+{
+ int i, j;
+ unsigned long m;
+ compat_ulong_t um;
+ unsigned long nr_compat_longs;
+
+ /* align bitmap up to nearest compat_long_t boundary */
+ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
+
+ if (verify_area(VERIFY_WRITE, umask, bitmap_size / 8))
+ return -EFAULT;
+
+ nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
+
+ for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) {
+ m = *mask++;
+
+ for (j = 0; j < sizeof(m)/sizeof(um); j++) {
+ um = m;
+
+ /*
+ * We dont want to write past the end of the userspace
+ * bitmap.
+ */
+ if (nr_compat_longs-- > 0) {
+ if (__put_user(um, umask))
+ return -EFAULT;
+ }
+
+ umask++;
+ m >>= 4*sizeof(um);
+ m >>= 4*sizeof(um);
+ }
+ }
+
+ return 0;
+}
diff -puN include/linux/compat.h~compat_bitmap include/linux/compat.h
--- gr_work/include/linux/compat.h~compat_bitmap 2004-06-16 10:32:11.595272136 -0500
+++ gr_work-anton/include/linux/compat.h 2004-06-16 10:32:11.608270080 -0500
@@ -130,5 +130,15 @@ asmlinkage long compat_sys_select(int n,
compat_ulong_t __user *outp, compat_ulong_t __user *exp,
struct compat_timeval __user *tvp);

+#define BITS_PER_COMPAT_LONG (8*sizeof(compat_long_t))
+
+#define BITS_TO_COMPAT_LONGS(bits) \
+ (((bits)+BITS_PER_COMPAT_LONG-1)/BITS_PER_COMPAT_LONG)
+
+long compat_get_bitmap(unsigned long *mask, compat_ulong_t __user *umask,
+ unsigned long bitmap_size);
+long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
+ unsigned long bitmap_size);
+
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */
_
-
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