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compat_{get,put}_bitmap(): use unsafe_{get,put}_user()

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unroll the inner loops, while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-05-30 00:29:38 -04:00
parent 9a46903792
commit 1e1fc13348
2 changed files with 29 additions and 55 deletions
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3
include/linux/compat.h
View File

@ -388,8 +388,7 @@ asmlinkage long compat_sys_wait4(compat_pid_t pid,
#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)
#define BITS_TO_COMPAT_LONGS(bits) DIV_ROUND_UP(bits, BITS_PER_COMPAT_LONG)
long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
unsigned long bitmap_size);

81
kernel/compat.c
View File

@ -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