linux/lib/parser.c
Alex Elder 77dd3b0bd1 lib/parser.c: avoid overflow in match_number()
The result of converting an integer value to another signed integer type
that's unable to represent the original value is implementation defined.
(See notes in section 6.3.1.3 of the C standard.)

In match_number(), the result of simple_strtol() (which returns type long)
is assigned to a value of type int.

Instead, handle the result of simple_strtol() in a well-defined way, and
return -ERANGE if the result won't fit in the int variable used to hold
the parsed result.

No current callers pay attention to the particular error value returned,
so this additional return code shouldn't do any harm.

[akpm@linux-foundation.org: coding-style tweaks]
Signed-off-by: Alex Elder <elder@inktank.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-06 03:04:56 +09:00

239 lines
6.2 KiB
C

/*
* lib/parser.c - simple parser for mount, etc. options.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/ctype.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/string.h>
/**
* match_one: - Determines if a string matches a simple pattern
* @s: the string to examine for presence of the pattern
* @p: the string containing the pattern
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Determines if the pattern @p is present in string @s. Can only
* match extremely simple token=arg style patterns. If the pattern is found,
* the location(s) of the arguments will be returned in the @args array.
*/
static int match_one(char *s, const char *p, substring_t args[])
{
char *meta;
int argc = 0;
if (!p)
return 1;
while(1) {
int len = -1;
meta = strchr(p, '%');
if (!meta)
return strcmp(p, s) == 0;
if (strncmp(p, s, meta-p))
return 0;
s += meta - p;
p = meta + 1;
if (isdigit(*p))
len = simple_strtoul(p, (char **) &p, 10);
else if (*p == '%') {
if (*s++ != '%')
return 0;
p++;
continue;
}
if (argc >= MAX_OPT_ARGS)
return 0;
args[argc].from = s;
switch (*p++) {
case 's': {
size_t str_len = strlen(s);
if (str_len == 0)
return 0;
if (len == -1 || len > str_len)
len = str_len;
args[argc].to = s + len;
break;
}
case 'd':
simple_strtol(s, &args[argc].to, 0);
goto num;
case 'u':
simple_strtoul(s, &args[argc].to, 0);
goto num;
case 'o':
simple_strtoul(s, &args[argc].to, 8);
goto num;
case 'x':
simple_strtoul(s, &args[argc].to, 16);
num:
if (args[argc].to == args[argc].from)
return 0;
break;
default:
return 0;
}
s = args[argc].to;
argc++;
}
}
/**
* match_token: - Find a token (and optional args) in a string
* @s: the string to examine for token/argument pairs
* @table: match_table_t describing the set of allowed option tokens and the
* arguments that may be associated with them. Must be terminated with a
* &struct match_token whose pattern is set to the NULL pointer.
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Detects which if any of a set of token strings has been passed
* to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
* format identifiers which will be taken into account when matching the
* tokens, and whose locations will be returned in the @args array.
*/
int match_token(char *s, const match_table_t table, substring_t args[])
{
const struct match_token *p;
for (p = table; !match_one(s, p->pattern, args) ; p++)
;
return p->token;
}
/**
* match_number: scan a number in the given base from a substring_t
* @s: substring to be scanned
* @result: resulting integer on success
* @base: base to use when converting string
*
* Description: Given a &substring_t and a base, attempts to parse the substring
* as a number in that base. On success, sets @result to the integer represented
* by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
*/
static int match_number(substring_t *s, int *result, int base)
{
char *endp;
char *buf;
int ret;
long val;
size_t len = s->to - s->from;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
memcpy(buf, s->from, len);
buf[len] = '\0';
ret = 0;
val = simple_strtol(buf, &endp, base);
if (endp == buf)
ret = -EINVAL;
else if (val < (long)INT_MIN || val > (long)INT_MAX)
ret = -ERANGE;
else
*result = (int) val;
kfree(buf);
return ret;
}
/**
* match_int: - scan a decimal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a decimal integer. On
* success, sets @result to the integer represented by the string and returns 0.
* Returns either -ENOMEM or -EINVAL on failure.
*/
int match_int(substring_t *s, int *result)
{
return match_number(s, result, 0);
}
/**
* match_octal: - scan an octal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as an octal integer. On
* success, sets @result to the integer represented by the string and returns
* 0. Returns either -ENOMEM or -EINVAL on failure.
*/
int match_octal(substring_t *s, int *result)
{
return match_number(s, result, 8);
}
/**
* match_hex: - scan a hex representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
* On success, sets @result to the integer represented by the string and
* returns 0. Returns either -ENOMEM or -EINVAL on failure.
*/
int match_hex(substring_t *s, int *result)
{
return match_number(s, result, 16);
}
/**
* match_strlcpy: - Copy the characters from a substring_t to a sized buffer
* @dest: where to copy to
* @src: &substring_t to copy
* @size: size of destination buffer
*
* Description: Copy the characters in &substring_t @src to the
* c-style string @dest. Copy no more than @size - 1 characters, plus
* the terminating NUL. Return length of @src.
*/
size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
{
size_t ret = src->to - src->from;
if (size) {
size_t len = ret >= size ? size - 1 : ret;
memcpy(dest, src->from, len);
dest[len] = '\0';
}
return ret;
}
/**
* match_strdup: - allocate a new string with the contents of a substring_t
* @s: &substring_t to copy
*
* Description: Allocates and returns a string filled with the contents of
* the &substring_t @s. The caller is responsible for freeing the returned
* string with kfree().
*/
char *match_strdup(const substring_t *s)
{
size_t sz = s->to - s->from + 1;
char *p = kmalloc(sz, GFP_KERNEL);
if (p)
match_strlcpy(p, s, sz);
return p;
}
EXPORT_SYMBOL(match_token);
EXPORT_SYMBOL(match_int);
EXPORT_SYMBOL(match_octal);
EXPORT_SYMBOL(match_hex);
EXPORT_SYMBOL(match_strlcpy);
EXPORT_SYMBOL(match_strdup);