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authorAl Viro <viro@zeniv.linux.org.uk>2017-05-30 00:29:38 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2017-06-09 23:51:17 -0400
commit1e1fc133483ef3b56c20bf3cd9241146c41042f8 (patch)
tree6f4df10c1fcb97d3cdaf4c006e55dd08f8e3b16f /kernel/compat.c
parent9a4690379206695b63a175e227877490beb2eeda (diff)
downloadlinux-1e1fc133483ef3b56c20bf3cd9241146c41042f8.tar.bz2
compat_{get,put}_bitmap(): use unsafe_{get,put}_user()
unroll the inner loops, while we are at it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel/compat.c')
-rw-r--r--kernel/compat.c81
1 files changed, 28 insertions, 53 deletions
diff --git a/kernel/compat.c b/kernel/compat.c
index 860f674fa556..9c2a8f3788d5 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -871,84 +871,59 @@ int get_compat_sigevent(struct sigevent *event,
long compat_get_bitmap(unsigned long *mask, const 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);
+ nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
if (!access_ok(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) {
- nr_compat_longs--;
- if (__get_user(um, umask))
- return -EFAULT;
- } else {
- um = 0;
- }
-
- umask++;
- m |= (long)um << (j * BITS_PER_COMPAT_LONG);
- }
- *mask++ = m;
+ user_access_begin();
+ while (nr_compat_longs > 1) {
+ compat_ulong_t l1, l2;
+ unsafe_get_user(l1, umask++, Efault);
+ unsafe_get_user(l2, umask++, Efault);
+ *mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
+ nr_compat_longs -= 2;
}
-
+ if (nr_compat_longs)
+ unsafe_get_user(*mask, umask++, Efault);
+ user_access_end();
return 0;
+
+Efault:
+ user_access_end();
+ return -EFAULT;
}
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);
+ nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
if (!access_ok(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) {
- nr_compat_longs--;
- if (__put_user(um, umask))
- return -EFAULT;
- }
-
- umask++;
- m >>= 4*sizeof(um);
- m >>= 4*sizeof(um);
- }
+ user_access_begin();
+ while (nr_compat_longs > 1) {
+ unsigned long m = *mask++;
+ unsafe_put_user((compat_ulong_t)m, umask++, Efault);
+ unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
+ nr_compat_longs -= 2;
}
-
+ if (nr_compat_longs)
+ unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
+ user_access_end();
return 0;
+Efault:
+ user_access_end();
+ return -EFAULT;
}
void