mirror of
https://github.com/torvalds/linux.git
synced 2024-11-29 23:51:37 +00:00
3955768075
Prevent false positives in bch2_varint_decode_fast() Signed-off-by: Brett Holman <bholman.devel@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
122 lines
2.4 KiB
C
122 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/math.h>
|
|
#include <linux/string.h>
|
|
#include <asm/unaligned.h>
|
|
|
|
#ifdef CONFIG_VALGRIND
|
|
#include <valgrind/memcheck.h>
|
|
#endif
|
|
|
|
#include "varint.h"
|
|
|
|
/**
|
|
* bch2_varint_encode - encode a variable length integer
|
|
* @out - destination to encode to
|
|
* @v - unsigned integer to encode
|
|
*
|
|
* Returns the size in bytes of the encoded integer - at most 9 bytes
|
|
*/
|
|
int bch2_varint_encode(u8 *out, u64 v)
|
|
{
|
|
unsigned bits = fls64(v|1);
|
|
unsigned bytes = DIV_ROUND_UP(bits, 7);
|
|
|
|
if (likely(bytes < 9)) {
|
|
v <<= bytes;
|
|
v |= ~(~0 << (bytes - 1));
|
|
v = cpu_to_le64(v);
|
|
memcpy(out, &v, bytes);
|
|
} else {
|
|
*out++ = 255;
|
|
bytes = 9;
|
|
put_unaligned_le64(v, out);
|
|
}
|
|
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* bch2_varint_decode - encode a variable length integer
|
|
* @in - varint to decode
|
|
* @end - end of buffer to decode from
|
|
* @out - on success, decoded integer
|
|
*
|
|
* Returns the size in bytes of the decoded integer - or -1 on failure (would
|
|
* have read past the end of the buffer)
|
|
*/
|
|
int bch2_varint_decode(const u8 *in, const u8 *end, u64 *out)
|
|
{
|
|
unsigned bytes = likely(in < end)
|
|
? ffz(*in & 255) + 1
|
|
: 1;
|
|
u64 v;
|
|
|
|
if (unlikely(in + bytes > end))
|
|
return -1;
|
|
|
|
if (likely(bytes < 9)) {
|
|
v = 0;
|
|
memcpy(&v, in, bytes);
|
|
v = le64_to_cpu(v);
|
|
v >>= bytes;
|
|
} else {
|
|
v = get_unaligned_le64(++in);
|
|
}
|
|
|
|
*out = v;
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* bch2_varint_encode_fast - fast version of bch2_varint_encode
|
|
*
|
|
* This version assumes it's always safe to write 8 bytes to @out, even if the
|
|
* encoded integer would be smaller.
|
|
*/
|
|
int bch2_varint_encode_fast(u8 *out, u64 v)
|
|
{
|
|
unsigned bits = fls64(v|1);
|
|
unsigned bytes = DIV_ROUND_UP(bits, 7);
|
|
|
|
if (likely(bytes < 9)) {
|
|
v <<= bytes;
|
|
v |= ~(~0 << (bytes - 1));
|
|
} else {
|
|
*out++ = 255;
|
|
bytes = 9;
|
|
}
|
|
|
|
put_unaligned_le64(v, out);
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* bch2_varint_decode_fast - fast version of bch2_varint_decode
|
|
*
|
|
* This version assumes that it is safe to read at most 8 bytes past the end of
|
|
* @end (we still return an error if the varint extends past @end).
|
|
*/
|
|
int bch2_varint_decode_fast(const u8 *in, const u8 *end, u64 *out)
|
|
{
|
|
#ifdef CONFIG_VALGRIND
|
|
VALGRIND_MAKE_MEM_DEFINED(in, 8);
|
|
#endif
|
|
u64 v = get_unaligned_le64(in);
|
|
unsigned bytes = ffz(*in) + 1;
|
|
|
|
if (unlikely(in + bytes > end))
|
|
return -1;
|
|
|
|
if (likely(bytes < 9)) {
|
|
v >>= bytes;
|
|
v &= ~(~0ULL << (7 * bytes));
|
|
} else {
|
|
v = get_unaligned_le64(++in);
|
|
}
|
|
|
|
*out = v;
|
|
return bytes;
|
|
}
|