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linux/arch/alpha/lib/csum_partial_copy.c
Mikulas Patocka 0ef38d70d4 alpha: fix broken network checksum 
The patch 3ddc5b46a8 breaks networking on
alpha (there is a follow-up fix 5cfe8f1ba5,
but networking is still broken even with the second patch).

The patch 3ddc5b46a8 makes
csum_partial_copy_from_user check the pointer with access_ok. However,
csum_partial_copy_from_user is called also from csum_partial_copy_nocheck
and csum_partial_copy_nocheck is called on kernel pointers and it is
supposed not to check pointer validity.

This bug results in ssh session hangs if the system is loaded and bulk
data are printed to ssh terminal.

This patch fixes csum_partial_copy_nocheck to call set_fs(KERNEL_DS), so
that access_ok in csum_partial_copy_from_user accepts kernel-space
addresses.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
2014-01-31 09:21:55 -08:00

389 lines
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/*
* csum_partial_copy - do IP checksumming and copy
*
* (C) Copyright 1996 Linus Torvalds
* accelerated versions (and 21264 assembly versions ) contributed by
* Rick Gorton <rick.gorton@alpha-processor.com>
*
* Don't look at this too closely - you'll go mad. The things
* we do for performance..
*/
#include <linux/types.h>
#include <linux/string.h>
#include <asm/uaccess.h>
#define ldq_u(x,y) \
__asm__ __volatile__("ldq_u %0,%1":"=r" (x):"m" (*(const unsigned long *)(y)))
#define stq_u(x,y) \
__asm__ __volatile__("stq_u %1,%0":"=m" (*(unsigned long *)(y)):"r" (x))
#define extql(x,y,z) \
__asm__ __volatile__("extql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define extqh(x,y,z) \
__asm__ __volatile__("extqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define mskql(x,y,z) \
__asm__ __volatile__("mskql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define mskqh(x,y,z) \
__asm__ __volatile__("mskqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define insql(x,y,z) \
__asm__ __volatile__("insql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define insqh(x,y,z) \
__asm__ __volatile__("insqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
#define __get_user_u(x,ptr) \
({ \
long __guu_err; \
__asm__ __volatile__( \
"1: ldq_u %0,%2\n" \
"2:\n" \
".section __ex_table,\"a\"\n" \
" .long 1b - .\n" \
" lda %0,2b-1b(%1)\n" \
".previous" \
: "=r"(x), "=r"(__guu_err) \
: "m"(__m(ptr)), "1"(0)); \
__guu_err; \
})
#define __put_user_u(x,ptr) \
({ \
long __puu_err; \
__asm__ __volatile__( \
"1: stq_u %2,%1\n" \
"2:\n" \
".section __ex_table,\"a\"\n" \
" .long 1b - ." \
" lda $31,2b-1b(%0)\n" \
".previous" \
: "=r"(__puu_err) \
: "m"(__m(addr)), "rJ"(x), "0"(0)); \
__puu_err; \
})
static inline unsigned short from64to16(unsigned long x)
{
/* Using extract instructions is a bit more efficient
than the original shift/bitmask version. */
union {
unsigned long ul;
unsigned int ui[2];
unsigned short us[4];
} in_v, tmp_v, out_v;
in_v.ul = x;
tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1];
/* Since the bits of tmp_v.sh[3] are going to always be zero,
we don't have to bother to add that in. */
out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1]
+ (unsigned long) tmp_v.us[2];
/* Similarly, out_v.us[2] is always zero for the final add. */
return out_v.us[0] + out_v.us[1];
}
/*
* Ok. This isn't fun, but this is the EASY case.
*/
static inline unsigned long
csum_partial_cfu_aligned(const unsigned long __user *src, unsigned long *dst,
long len, unsigned long checksum,
int *errp)
{
unsigned long carry = 0;
int err = 0;
while (len >= 0) {
unsigned long word;
err |= __get_user(word, src);
checksum += carry;
src++;
checksum += word;
len -= 8;
carry = checksum < word;
*dst = word;
dst++;
}
len += 8;
checksum += carry;
if (len) {
unsigned long word, tmp;
err |= __get_user(word, src);
tmp = *dst;
mskql(word, len, word);
checksum += word;
mskqh(tmp, len, tmp);
carry = checksum < word;
*dst = word | tmp;
checksum += carry;
}
if (err && errp) *errp = err;
return checksum;
}
/*
* This is even less fun, but this is still reasonably
* easy.
*/
static inline unsigned long
csum_partial_cfu_dest_aligned(const unsigned long __user *src,
unsigned long *dst,
unsigned long soff,
long len, unsigned long checksum,
int *errp)
{
unsigned long first;
unsigned long word, carry;
unsigned long lastsrc = 7+len+(unsigned long)src;
int err = 0;
err |= __get_user_u(first,src);
carry = 0;
while (len >= 0) {
unsigned long second;
err |= __get_user_u(second, src+1);
extql(first, soff, word);
len -= 8;
src++;
extqh(second, soff, first);
checksum += carry;
word |= first;
first = second;
checksum += word;
*dst = word;
dst++;
carry = checksum < word;
}
len += 8;
checksum += carry;
if (len) {
unsigned long tmp;
unsigned long second;
err |= __get_user_u(second, lastsrc);
tmp = *dst;
extql(first, soff, word);
extqh(second, soff, first);
word |= first;
mskql(word, len, word);
checksum += word;
mskqh(tmp, len, tmp);
carry = checksum < word;
*dst = word | tmp;
checksum += carry;
}
if (err && errp) *errp = err;
return checksum;
}
/*
* This is slightly less fun than the above..
*/
static inline unsigned long
csum_partial_cfu_src_aligned(const unsigned long __user *src,
unsigned long *dst,
unsigned long doff,
long len, unsigned long checksum,
unsigned long partial_dest,
int *errp)
{
unsigned long carry = 0;
unsigned long word;
unsigned long second_dest;
int err = 0;
mskql(partial_dest, doff, partial_dest);
while (len >= 0) {
err |= __get_user(word, src);
len -= 8;
insql(word, doff, second_dest);
checksum += carry;
stq_u(partial_dest | second_dest, dst);
src++;
checksum += word;
insqh(word, doff, partial_dest);
carry = checksum < word;
dst++;
}
len += 8;
if (len) {
checksum += carry;
err |= __get_user(word, src);
mskql(word, len, word);
len -= 8;
checksum += word;
insql(word, doff, second_dest);
len += doff;
carry = checksum < word;
partial_dest |= second_dest;
if (len >= 0) {
stq_u(partial_dest, dst);
if (!len) goto out;
dst++;
insqh(word, doff, partial_dest);
}
doff = len;
}
ldq_u(second_dest, dst);
mskqh(second_dest, doff, second_dest);
stq_u(partial_dest | second_dest, dst);
out:
checksum += carry;
if (err && errp) *errp = err;
return checksum;
}
/*
* This is so totally un-fun that it's frightening. Don't
* look at this too closely, you'll go blind.
*/
static inline unsigned long
csum_partial_cfu_unaligned(const unsigned long __user * src,
unsigned long * dst,
unsigned long soff, unsigned long doff,
long len, unsigned long checksum,
unsigned long partial_dest,
int *errp)
{
unsigned long carry = 0;
unsigned long first;
unsigned long lastsrc;
int err = 0;
err |= __get_user_u(first, src);
lastsrc = 7+len+(unsigned long)src;
mskql(partial_dest, doff, partial_dest);
while (len >= 0) {
unsigned long second, word;
unsigned long second_dest;
err |= __get_user_u(second, src+1);
extql(first, soff, word);
checksum += carry;
len -= 8;
extqh(second, soff, first);
src++;
word |= first;
first = second;
insql(word, doff, second_dest);
checksum += word;
stq_u(partial_dest | second_dest, dst);
carry = checksum < word;
insqh(word, doff, partial_dest);
dst++;
}
len += doff;
checksum += carry;
if (len >= 0) {
unsigned long second, word;
unsigned long second_dest;
err |= __get_user_u(second, lastsrc);
extql(first, soff, word);
extqh(second, soff, first);
word |= first;
first = second;
mskql(word, len-doff, word);
checksum += word;
insql(word, doff, second_dest);
carry = checksum < word;
stq_u(partial_dest | second_dest, dst);
if (len) {
ldq_u(second_dest, dst+1);
insqh(word, doff, partial_dest);
mskqh(second_dest, len, second_dest);
stq_u(partial_dest | second_dest, dst+1);
}
checksum += carry;
} else {
unsigned long second, word;
unsigned long second_dest;
err |= __get_user_u(second, lastsrc);
extql(first, soff, word);
extqh(second, soff, first);
word |= first;
ldq_u(second_dest, dst);
mskql(word, len-doff, word);
checksum += word;
mskqh(second_dest, len, second_dest);
carry = checksum < word;
insql(word, doff, word);
stq_u(partial_dest | word | second_dest, dst);
checksum += carry;
}
if (err && errp) *errp = err;
return checksum;
}
__wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len,
__wsum sum, int *errp)
{
unsigned long checksum = (__force u32) sum;
unsigned long soff = 7 & (unsigned long) src;
unsigned long doff = 7 & (unsigned long) dst;
if (len) {
if (!access_ok(VERIFY_READ, src, len)) {
if (errp) *errp = -EFAULT;
memset(dst, 0, len);
return sum;
}
if (!doff) {
if (!soff)
checksum = csum_partial_cfu_aligned(
(const unsigned long __user *) src,
(unsigned long *) dst,
len-8, checksum, errp);
else
checksum = csum_partial_cfu_dest_aligned(
(const unsigned long __user *) src,
(unsigned long *) dst,
soff, len-8, checksum, errp);
} else {
unsigned long partial_dest;
ldq_u(partial_dest, dst);
if (!soff)
checksum = csum_partial_cfu_src_aligned(
(const unsigned long __user *) src,
(unsigned long *) dst,
doff, len-8, checksum,
partial_dest, errp);
else
checksum = csum_partial_cfu_unaligned(
(const unsigned long __user *) src,
(unsigned long *) dst,
soff, doff, len-8, checksum,
partial_dest, errp);
}
checksum = from64to16 (checksum);
}
return (__force __wsum)checksum;
}
__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
__wsum checksum;
mm_segment_t oldfs = get_fs();
set_fs(KERNEL_DS);
checksum = csum_partial_copy_from_user((__force const void __user *)src,
dst, len, sum, NULL);
set_fs(oldfs);
return checksum;
}
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