forked from luck/tmp_suning_uos_patched
lib: vsprintf: Fix handling of number field widths in vsscanf
[ Upstream commit 900fdc4573766dd43b847b4f54bd4a1ee2bc7360 ] The existing code attempted to handle numbers by doing a strto[u]l(), ignoring the field width, and then repeatedly dividing to extract the field out of the full converted value. If the string contains a run of valid digits longer than will fit in a long or long long, this would overflow and no amount of dividing can recover the correct value. This patch fixes vsscanf() to obey number field widths when parsing the number. A new _parse_integer_limit() is added that takes a limit for the number of characters to parse. The number field conversion in vsscanf is changed to use this new function. If a number starts with a radix prefix, the field width must be long enough for at last one digit after the prefix. If not, it will be handled like this: sscanf("0x4", "%1i", &i): i=0, scanning continues with the 'x' sscanf("0x4", "%2i", &i): i=0, scanning continues with the '4' This is consistent with the observed behaviour of userland sscanf. Note that this patch does NOT fix the problem of a single field value overflowing the target type. So for example: sscanf("123456789abcdef", "%x", &i); Will not produce the correct result because the value obviously overflows INT_MAX. But sscanf will report a successful conversion. Note that where a very large number is used to mean "unlimited", the value INT_MAX is used for consistency with the behaviour of vsnprintf(). Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210514161206.30821-2-rf@opensource.cirrus.com Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
f8c3236890
commit
9e914f59cc
|
@ -39,20 +39,22 @@ const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
|
|||
|
||||
/*
|
||||
* Convert non-negative integer string representation in explicitly given radix
|
||||
* to an integer.
|
||||
* to an integer. A maximum of max_chars characters will be converted.
|
||||
*
|
||||
* Return number of characters consumed maybe or-ed with overflow bit.
|
||||
* If overflow occurs, result integer (incorrect) is still returned.
|
||||
*
|
||||
* Don't you dare use this function.
|
||||
*/
|
||||
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
|
||||
unsigned int _parse_integer_limit(const char *s, unsigned int base, unsigned long long *p,
|
||||
size_t max_chars)
|
||||
{
|
||||
unsigned long long res;
|
||||
unsigned int rv;
|
||||
|
||||
res = 0;
|
||||
rv = 0;
|
||||
while (1) {
|
||||
while (max_chars--) {
|
||||
unsigned int c = *s;
|
||||
unsigned int lc = c | 0x20; /* don't tolower() this line */
|
||||
unsigned int val;
|
||||
|
@ -82,6 +84,11 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long
|
|||
return rv;
|
||||
}
|
||||
|
||||
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
|
||||
{
|
||||
return _parse_integer_limit(s, base, p, INT_MAX);
|
||||
}
|
||||
|
||||
static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
|
||||
{
|
||||
unsigned long long _res;
|
||||
|
|
|
@ -4,6 +4,8 @@
|
|||
|
||||
#define KSTRTOX_OVERFLOW (1U << 31)
|
||||
const char *_parse_integer_fixup_radix(const char *s, unsigned int *base);
|
||||
unsigned int _parse_integer_limit(const char *s, unsigned int base, unsigned long long *res,
|
||||
size_t max_chars);
|
||||
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *res);
|
||||
|
||||
#endif
|
||||
|
|
|
@ -53,6 +53,31 @@
|
|||
#include <linux/string_helpers.h>
|
||||
#include "kstrtox.h"
|
||||
|
||||
static unsigned long long simple_strntoull(const char *startp, size_t max_chars,
|
||||
char **endp, unsigned int base)
|
||||
{
|
||||
const char *cp;
|
||||
unsigned long long result = 0ULL;
|
||||
size_t prefix_chars;
|
||||
unsigned int rv;
|
||||
|
||||
cp = _parse_integer_fixup_radix(startp, &base);
|
||||
prefix_chars = cp - startp;
|
||||
if (prefix_chars < max_chars) {
|
||||
rv = _parse_integer_limit(cp, base, &result, max_chars - prefix_chars);
|
||||
/* FIXME */
|
||||
cp += (rv & ~KSTRTOX_OVERFLOW);
|
||||
} else {
|
||||
/* Field too short for prefix + digit, skip over without converting */
|
||||
cp = startp + max_chars;
|
||||
}
|
||||
|
||||
if (endp)
|
||||
*endp = (char *)cp;
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* simple_strtoull - convert a string to an unsigned long long
|
||||
* @cp: The start of the string
|
||||
|
@ -63,18 +88,7 @@
|
|||
*/
|
||||
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
|
||||
{
|
||||
unsigned long long result;
|
||||
unsigned int rv;
|
||||
|
||||
cp = _parse_integer_fixup_radix(cp, &base);
|
||||
rv = _parse_integer(cp, base, &result);
|
||||
/* FIXME */
|
||||
cp += (rv & ~KSTRTOX_OVERFLOW);
|
||||
|
||||
if (endp)
|
||||
*endp = (char *)cp;
|
||||
|
||||
return result;
|
||||
return simple_strntoull(cp, INT_MAX, endp, base);
|
||||
}
|
||||
EXPORT_SYMBOL(simple_strtoull);
|
||||
|
||||
|
@ -109,6 +123,21 @@ long simple_strtol(const char *cp, char **endp, unsigned int base)
|
|||
}
|
||||
EXPORT_SYMBOL(simple_strtol);
|
||||
|
||||
static long long simple_strntoll(const char *cp, size_t max_chars, char **endp,
|
||||
unsigned int base)
|
||||
{
|
||||
/*
|
||||
* simple_strntoull() safely handles receiving max_chars==0 in the
|
||||
* case cp[0] == '-' && max_chars == 1.
|
||||
* If max_chars == 0 we can drop through and pass it to simple_strntoull()
|
||||
* and the content of *cp is irrelevant.
|
||||
*/
|
||||
if (*cp == '-' && max_chars > 0)
|
||||
return -simple_strntoull(cp + 1, max_chars - 1, endp, base);
|
||||
|
||||
return simple_strntoull(cp, max_chars, endp, base);
|
||||
}
|
||||
|
||||
/**
|
||||
* simple_strtoll - convert a string to a signed long long
|
||||
* @cp: The start of the string
|
||||
|
@ -119,10 +148,7 @@ EXPORT_SYMBOL(simple_strtol);
|
|||
*/
|
||||
long long simple_strtoll(const char *cp, char **endp, unsigned int base)
|
||||
{
|
||||
if (*cp == '-')
|
||||
return -simple_strtoull(cp + 1, endp, base);
|
||||
|
||||
return simple_strtoull(cp, endp, base);
|
||||
return simple_strntoll(cp, INT_MAX, endp, base);
|
||||
}
|
||||
EXPORT_SYMBOL(simple_strtoll);
|
||||
|
||||
|
@ -3442,25 +3468,13 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
|
|||
break;
|
||||
|
||||
if (is_sign)
|
||||
val.s = qualifier != 'L' ?
|
||||
simple_strtol(str, &next, base) :
|
||||
simple_strtoll(str, &next, base);
|
||||
val.s = simple_strntoll(str,
|
||||
field_width >= 0 ? field_width : INT_MAX,
|
||||
&next, base);
|
||||
else
|
||||
val.u = qualifier != 'L' ?
|
||||
simple_strtoul(str, &next, base) :
|
||||
simple_strtoull(str, &next, base);
|
||||
|
||||
if (field_width > 0 && next - str > field_width) {
|
||||
if (base == 0)
|
||||
_parse_integer_fixup_radix(str, &base);
|
||||
while (next - str > field_width) {
|
||||
if (is_sign)
|
||||
val.s = div_s64(val.s, base);
|
||||
else
|
||||
val.u = div_u64(val.u, base);
|
||||
--next;
|
||||
}
|
||||
}
|
||||
val.u = simple_strntoull(str,
|
||||
field_width >= 0 ? field_width : INT_MAX,
|
||||
&next, base);
|
||||
|
||||
switch (qualifier) {
|
||||
case 'H': /* that's 'hh' in format */
|
||||
|
|
Loading…
Reference in New Issue
Block a user