Commit d1bc05b7 authored by Benjamin Gray's avatar Benjamin Gray Committed by Michael Ellerman
Browse files

selftests/powerpc: Parse long/unsigned long value safely 



Often a file is expected to hold an integral value. Existing functions
will use a C stdlib function like atoi or strtol to parse the file.
These operations are error prone, with complicated error conditions
(atoi returns 0 if not a number, and is undefined behaviour if not in
range. strtol returns 0 if not a number, and LONG_MIN/MAX if not in
range + sets errno to ERANGE).

Signed-off-by: default avatarBenjamin Gray <bgray@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230203003947.38033-4-bgray@linux.ibm.com
parent 121d340b

tools/testing/selftests/powerpc/include/utils.h

+7 −0
Original line number Diff line number Diff line
@@ -33,6 +33,13 @@ void *get_auxv_entry(int type); 


int pick_online_cpu(void);



int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base);

int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base);

int parse_int(const char *buffer, size_t count, int *result, int base);

int parse_uint(const char *buffer, size_t count, unsigned int *result, int base);

int parse_long(const char *buffer, size_t count, long *result, int base);

int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base);



int read_file(const char *path, char *buf, size_t count, size_t *len);

int write_file(const char *path, const char *buf, size_t count);

int read_debugfs_file(const char *debugfs_file, char *buf, size_t count);

tools/testing/selftests/powerpc/pmu/lib.c

+2 −4
Original line number Diff line number Diff line
@@ -192,7 +192,6 @@ bool require_paranoia_below(int level) 
{

	int err;

	long current;

	char *end;

	char buf[16] = {0};



	err = read_file(PARANOID_PATH, buf, sizeof(buf) - 1, NULL);
@@ -201,9 +200,8 @@ bool require_paranoia_below(int level) 
		return false;

	}



	current = strtol(buf, &end, 10);



	if (end == buf) {

	err = parse_long(buf, sizeof(buf), &current, 10);

	if (err) {

		printf("Couldn't parse " PARANOID_PATH "?\n");

		return false;

	}

tools/testing/selftests/powerpc/utils.c

+123 −3
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <elf.h>

#include <errno.h>

#include <fcntl.h>

#include <inttypes.h>

#include <limits.h>

#include <link.h>

#include <sched.h>

#include <stdio.h>
@@ -123,6 +125,126 @@ int write_debugfs_file(const char *subpath, const char *buf, size_t count) 
	return write_file(path, buf, count);

}



static int validate_int_parse(const char *buffer, size_t count, char *end)

{

	int err = 0;



	/* Require at least one digit */

	if (end == buffer) {

		err = -EINVAL;

		goto out;

	}



	/* Require all remaining characters be whitespace-ish */

	for (; end < buffer + count; end++) {

		if (*end == '\0')

			break;



		if (*end != ' ' && *end != '\n') {

			err = -EINVAL;

			goto out;

		}

	}



out:

	errno = -err;

	return err;

}



static int parse_bounded_int(const char *buffer, size_t count, intmax_t *result,

			     int base, intmax_t min, intmax_t max)

{

	int err;

	char *end;



	errno = 0;

	*result = strtoimax(buffer, &end, base);



	if (errno)

		return -errno;



	err = validate_int_parse(buffer, count, end);

	if (err)

		goto out;



	if (*result < min || *result > max)

		err = -EOVERFLOW;



out:

	errno = -err;

	return err;

}



static int parse_bounded_uint(const char *buffer, size_t count, uintmax_t *result,

			      int base, uintmax_t max)

{

	int err = 0;

	char *end;



	errno = 0;

	*result = strtoumax(buffer, &end, base);



	if (errno)

		return -errno;



	err = validate_int_parse(buffer, count, end);

	if (err)

		goto out;



	if (*result > max)

		err = -EOVERFLOW;



out:

	errno = -err;

	return err;

}



int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base)

{

	return parse_bounded_int(buffer, count, result, base, INTMAX_MIN, INTMAX_MAX);

}



int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base)

{

	return parse_bounded_uint(buffer, count, result, base, UINTMAX_MAX);

}



int parse_int(const char *buffer, size_t count, int *result, int base)

{

	intmax_t parsed;

	int err = parse_bounded_int(buffer, count, &parsed, base, INT_MIN, INT_MAX);



	*result = parsed;

	return err;

}



int parse_uint(const char *buffer, size_t count, unsigned int *result, int base)

{

	uintmax_t parsed;

	int err = parse_bounded_uint(buffer, count, &parsed, base, UINT_MAX);



	*result = parsed;

	return err;

}



int parse_long(const char *buffer, size_t count, long *result, int base)

{

	intmax_t parsed;

	int err = parse_bounded_int(buffer, count, &parsed, base, LONG_MIN, LONG_MAX);



	*result = parsed;

	return err;

}



int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base)

{

	uintmax_t parsed;

	int err = parse_bounded_uint(buffer, count, &parsed, base, ULONG_MAX);



	*result = parsed;

	return err;

}



void *find_auxv_entry(int type, char *auxv)

{

	ElfW(auxv_t) *p;
@@ -224,9 +346,7 @@ int read_debugfs_int(const char *debugfs_file, int *result) 
	if (err)

		return err;



	*result = atoi(value);



	return 0;

	return parse_int(value, sizeof(value), result, 10);

}



int write_debugfs_int(const char *debugfs_file, int result)