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check_kernel_printf.c
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/*
* Copyright (C) 2015 Rasmus Villemoes.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
*/
#define _GNU_SOURCE
#include <assert.h>
#include <ctype.h>
#include <string.h>
#include "smatch.h"
#include "smatch_slist.h"
#define spam(args...) do { \
if (option_spammy) \
sm_msg(args); \
} while (0)
static int my_id;
/*
* Much of this is taken directly from the kernel (mostly vsprintf.c),
* with a few modifications here and there.
*/
#define KERN_SOH_ASCII '\001'
typedef unsigned char u8;
typedef signed short s16;
#define SIGN 1 /* unsigned/signed, must be 1 */
#define LEFT 2 /* left justified */
#define PLUS 4 /* show plus */
#define SPACE 8 /* space if plus */
#define ZEROPAD 16 /* pad with zero, must be 16 == '0' - ' ' */
#define SMALL 32 /* use lowercase in hex (must be 32 == 0x20) */
#define SPECIAL 64 /* prefix hex with "0x", octal with "0" */
enum format_type {
FORMAT_TYPE_NONE, /* Just a string part */
FORMAT_TYPE_WIDTH,
FORMAT_TYPE_PRECISION,
FORMAT_TYPE_CHAR,
FORMAT_TYPE_STR,
FORMAT_TYPE_PTR,
FORMAT_TYPE_PERCENT_CHAR,
FORMAT_TYPE_INVALID,
FORMAT_TYPE_LONG_LONG,
FORMAT_TYPE_ULONG,
FORMAT_TYPE_LONG,
FORMAT_TYPE_UBYTE,
FORMAT_TYPE_BYTE,
FORMAT_TYPE_USHORT,
FORMAT_TYPE_SHORT,
FORMAT_TYPE_UINT,
FORMAT_TYPE_INT,
FORMAT_TYPE_SIZE_T,
FORMAT_TYPE_PTRDIFF,
FORMAT_TYPE_NRCHARS, /* Reintroduced for this checker */
FORMAT_TYPE_FLOAT, /* for various floating point formatters */
};
struct printf_spec {
unsigned int type:8; /* format_type enum */
signed int field_width:24; /* width of output field */
unsigned int flags:8; /* flags to number() */
unsigned int base:8; /* number base, 8, 10 or 16 only */
signed int precision:16; /* # of digits/chars */
} __packed;
#define FIELD_WIDTH_MAX ((1 << 23) - 1)
#define PRECISION_MAX ((1 << 15) - 1)
extern char __check_printf_spec[1-2*(sizeof(struct printf_spec) != 8)];
static int
skip_atoi(const char **s)
{
int i = 0;
while (isdigit(**s))
i = i*10 + *((*s)++) - '0';
return i;
}
static int
format_decode(const char *fmt, struct printf_spec *spec)
{
const char *start = fmt;
char qualifier;
/* we finished early by reading the field width */
if (spec->type == FORMAT_TYPE_WIDTH) {
if (spec->field_width < 0) {
spec->field_width = -spec->field_width;
spec->flags |= LEFT;
}
spec->type = FORMAT_TYPE_NONE;
goto precision;
}
/* we finished early by reading the precision */
if (spec->type == FORMAT_TYPE_PRECISION) {
if (spec->precision < 0)
spec->precision = 0;
spec->type = FORMAT_TYPE_NONE;
goto qualifier;
}
/* By default */
spec->type = FORMAT_TYPE_NONE;
for (; *fmt ; ++fmt) {
if (*fmt == '%')
break;
}
/* Return the current non-format string */
if (fmt != start || !*fmt)
return fmt - start;
/* Process flags */
spec->flags = 0;
while (1) { /* this also skips first '%' */
bool found = true;
++fmt;
switch (*fmt) {
case '-': spec->flags |= LEFT; break;
case '+': spec->flags |= PLUS; break;
case ' ': spec->flags |= SPACE; break;
case '#': spec->flags |= SPECIAL; break;
case '0': spec->flags |= ZEROPAD; break;
default: found = false;
}
if (!found)
break;
}
/* get field width */
spec->field_width = -1;
if (isdigit(*fmt))
spec->field_width = skip_atoi(&fmt);
else if (*fmt == '*') {
/* it's the next argument */
spec->type = FORMAT_TYPE_WIDTH;
return ++fmt - start;
}
precision:
/* get the precision */
spec->precision = -1;
if (*fmt == '.') {
++fmt;
if (isdigit(*fmt)) {
spec->precision = skip_atoi(&fmt);
if (spec->precision < 0)
spec->precision = 0;
} else if (*fmt == '*') {
/* it's the next argument */
spec->type = FORMAT_TYPE_PRECISION;
return ++fmt - start;
}
}
qualifier:
/* get the conversion qualifier */
qualifier = 0;
if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
_tolower(*fmt) == 'z' || *fmt == 't') {
qualifier = *fmt++;
if (qualifier == *fmt) {
if (qualifier == 'l') {
qualifier = 'L';
++fmt;
} else if (qualifier == 'h') {
qualifier = 'H';
++fmt;
} else {
sm_warning("invalid repeated qualifier '%c'", *fmt);
}
}
}
/* default base */
spec->base = 10;
switch (*fmt) {
case 'c':
if (qualifier)
sm_warning("qualifier '%c' ignored for %%c specifier", qualifier);
spec->type = FORMAT_TYPE_CHAR;
return ++fmt - start;
case 's':
if (qualifier && qualifier != 'l')
sm_warning("qualifier '%c' ignored for %%s specifier", qualifier);
spec->type = FORMAT_TYPE_STR;
return ++fmt - start;
case 'p':
spec->type = FORMAT_TYPE_PTR;
return ++fmt - start;
case '%':
spec->type = FORMAT_TYPE_PERCENT_CHAR;
return ++fmt - start;
/* integer number formats - set up the flags and "break" */
case 'o':
spec->base = 8;
break;
case 'x':
spec->flags |= SMALL;
case 'X':
spec->base = 16;
break;
case 'd':
case 'i':
spec->flags |= SIGN;
case 'u':
break;
case 'n':
spec->type = FORMAT_TYPE_NRCHARS;
return ++fmt - start;
case 'a': case 'A':
case 'e': case 'E':
case 'f': case 'F':
case 'g': case 'G':
spec->type = FORMAT_TYPE_FLOAT;
return ++fmt - start;
default:
spec->type = FORMAT_TYPE_INVALID;
/* Unlike the kernel code, we 'consume' the invalid
* character so that it can get included in the
* report. After that, we bail out. */
return ++fmt - start;
}
if (qualifier == 'L')
spec->type = FORMAT_TYPE_LONG_LONG;
else if (qualifier == 'l') {
if (spec->flags & SIGN)
spec->type = FORMAT_TYPE_LONG;
else
spec->type = FORMAT_TYPE_ULONG;
} else if (_tolower(qualifier) == 'z') {
spec->type = FORMAT_TYPE_SIZE_T;
} else if (qualifier == 't') {
spec->type = FORMAT_TYPE_PTRDIFF;
} else if (qualifier == 'H') {
if (spec->flags & SIGN)
spec->type = FORMAT_TYPE_BYTE;
else
spec->type = FORMAT_TYPE_UBYTE;
} else if (qualifier == 'h') {
if (spec->flags & SIGN)
spec->type = FORMAT_TYPE_SHORT;
else
spec->type = FORMAT_TYPE_USHORT;
} else {
if (spec->flags & SIGN)
spec->type = FORMAT_TYPE_INT;
else
spec->type = FORMAT_TYPE_UINT;
}
return ++fmt - start;
}
static int is_struct_tag(struct symbol *type, const char *tag)
{
return type->type == SYM_STRUCT && type->ident && !strcmp(type->ident->name, tag);
}
static int has_struct_tag(struct symbol *type, const char *tag)
{
struct symbol *tmp;
if (type->type == SYM_STRUCT)
return is_struct_tag(type, tag);
if (type->type == SYM_UNION) {
FOR_EACH_PTR(type->symbol_list, tmp) {
tmp = get_real_base_type(tmp);
if (tmp && is_struct_tag(tmp, tag))
return 1;
} END_FOR_EACH_PTR(tmp);
}
return 0;
}
static int is_char_type(struct symbol *type)
{
return type == &uchar_ctype || type == &char_ctype || type == &schar_ctype;
}
/*
* I have absolutely no idea if this is how one is supposed to get the
* symbol representing a typedef, but it seems to work.
*/
struct typedef_lookup {
const char *name;
struct symbol *sym;
int failed;
};
static struct symbol *_typedef_lookup(const char *name)
{
struct ident *id;
struct symbol *node;
id = built_in_ident(name);
if (!id)
return NULL;
node = lookup_symbol(id, NS_TYPEDEF);
if (!node || node->type != SYM_NODE)
return NULL;
return get_real_base_type(node);
}
static void typedef_lookup(struct typedef_lookup *tl)
{
if (tl->sym || tl->failed)
return;
tl->sym = _typedef_lookup(tl->name);
if (!tl->sym) {
sm_perror(" could not find typedef '%s'", tl->name);
tl->failed = 1;
}
}
static void ip4(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
enum { ENDIAN_BIG, ENDIAN_LITTLE, ENDIAN_HOST } endian = ENDIAN_BIG;
assert(fmt[0] == 'i' || fmt[0] == 'I');
assert(fmt[1] == '4');
if (isalnum(fmt[2])) {
switch (fmt[2]) {
case 'h':
endian = ENDIAN_HOST;
break;
case 'l':
endian = ENDIAN_LITTLE;
break;
case 'n':
case 'b':
endian = ENDIAN_BIG;
break;
default:
sm_warning("'%%p%c4' can only be followed by one of [hnbl], not '%c'", fmt[0], fmt[2]);
}
if (isalnum(fmt[3]))
sm_warning("'%%p%c4' can only be followed by precisely one of [hnbl]", fmt[0]);
}
if (type->ctype.modifiers & MOD_NODEREF)
sm_error("passing __user pointer to '%%p%c4'", fmt[0]);
/*
* If we have a pointer to char/u8/s8, we expect the caller to
* handle endianness; I don't think there's anything we can
* do. I'd like to check that if we're passed a pointer to a
* __bitwise u32 (most likely a __be32), we should have endian
* == ENDIAN_BIG. But I can't figure out how to get that
* information (it also seems to require ensuring certain
* macros are defined). But struct in_addr certainly consists
* of only a single __be32, so in that case we can do a check.
*/
if (is_char_type(basetype))
return;
if (is_struct_tag(basetype, "in_addr") && endian != ENDIAN_BIG)
sm_warning("passing struct in_addr* to '%%p%c4%c', is the endianness ok?", fmt[0], fmt[2]);
/* ... */
}
static void ip6(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(fmt[0] == 'i' || fmt[0] == 'I');
assert(fmt[1] == '6');
if (isalnum(fmt[2])) {
if (fmt[2] != 'c')
sm_warning("'%%p%c6' can only be followed by c", fmt[0]);
else if (fmt[0] == 'i')
sm_warning("'%%pi6' does not allow flag c");
if (isalnum(fmt[3]))
sm_warning("'%%p%c6%c' cannot be followed by other alphanumerics", fmt[0], fmt[2]);
}
if (type->ctype.modifiers & MOD_NODEREF)
sm_error("passing __user pointer to '%%p%c6'", fmt[0]);
}
static void ipS(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
const char *f;
assert(tolower(fmt[0]) == 'i');
assert(fmt[1] == 'S');
for (f = fmt+2; isalnum(*f); ++f) {
/* It's probably too anal checking for duplicate flags. */
if (!strchr("pfschnbl", *f))
sm_warning("'%%p%cS' cannot be followed by '%c'", fmt[0], *f);
}
/*
* XXX: Should we also allow passing a pointer to a union, one
* member of which is a struct sockaddr? It may be slightly
* cleaner actually passing &u.raw instead of just &u, though
* the generated code is of course exactly the same. For now,
* we do accept struct sockaddr_in and struct sockaddr_in6,
* since those are easy to handle and rather harmless.
*/
if (!has_struct_tag(basetype, "sockaddr") &&
!has_struct_tag(basetype, "sockaddr_in") &&
!has_struct_tag(basetype, "sockaddr_in6") &&
!has_struct_tag(basetype, "__kernel_sockaddr_storage"))
sm_error("'%%p%cS' expects argument of type struct sockaddr *, "
"argument %d has type '%s'", fmt[0], vaidx, type_to_str(type));
}
static void hex_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(fmt[0] == 'h');
if (isalnum(fmt[1])) {
if (!strchr("CDN", fmt[1]))
sm_warning("'%%ph' cannot be followed by '%c'", fmt[1]);
if (isalnum(fmt[2]))
sm_warning("'%%ph' can be followed by at most one of [CDN], and no other alphanumerics");
}
if (type->ctype.modifiers & MOD_NODEREF)
sm_error("passing __user pointer to %%ph");
}
static void escaped_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(fmt[0] == 'E');
while (isalnum(*++fmt)) {
if (!strchr("achnops", *fmt))
sm_warning("%%pE can only be followed by a combination of [achnops]");
}
if (type->ctype.modifiers & MOD_NODEREF)
sm_error("passing __user pointer to %%pE");
}
static void resource_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(tolower(fmt[0]) == 'r');
if (!is_struct_tag(basetype, "resource")) {
sm_error("'%%p%c' expects argument of type struct resource *, "
"but argument %d has type '%s'", fmt[0], vaidx, type_to_str(type));
}
if (isalnum(fmt[1]))
sm_warning("'%%p%c' cannot be followed by '%c'", fmt[0], fmt[1]);
}
static void mac_address_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(tolower(fmt[0]) == 'm');
if (isalnum(fmt[1])) {
if (!(fmt[1] == 'F' || fmt[1] == 'R'))
sm_warning("'%%p%c' cannot be followed by '%c'", fmt[0], fmt[1]);
if (fmt[0] == 'm' && fmt[1] == 'F')
sm_warning("it is pointless to pass flag F to %%pm");
if (isalnum(fmt[2]))
sm_warning("'%%p%c%c' cannot be followed by other alphanumeric", fmt[0], fmt[1]);
}
/* Technically, bdaddr_t is a typedef for an anonymous struct, but this still seems to work. */
if (!is_char_type(basetype) && !is_struct_tag(basetype, "bdaddr_t") && basetype != &void_ctype) {
sm_warning("'%%p%c' expects argument of type u8 * or bdaddr_t *, argument %d has type '%s'",
fmt[0], vaidx, type_to_str(type));
}
if (type->ctype.modifiers & MOD_NODEREF)
sm_error("passing __user pointer to '%%p%c'", fmt[0]);
}
static void dentry_file(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
const char *tag;
assert(tolower(fmt[0]) == 'd');
tag = fmt[0] == 'd' ? "dentry" : "file";
if (isalnum(fmt[1])) {
if (!strchr("234", fmt[1]))
sm_warning("'%%p%c' can only be followed by one of [234]", fmt[0]);
if (isalnum(fmt[2]))
sm_warning("'%%p%c%c' cannot be followed by '%c'", fmt[0], fmt[1], fmt[2]);
}
if (!is_struct_tag(basetype, tag))
sm_error("'%%p%c' expects argument of type struct '%s*', argument %d has type '%s'",
fmt[0], tag, vaidx, type_to_str(type));
}
static void time_and_date(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(tolower(fmt[0]) == 't');
if (fmt[1] == 'R' && !is_struct_tag(basetype, "rtc_time"))
sm_error("'%%ptR' expects argument of type struct 'rtc_time', argument %d has type '%s'",
vaidx, type_to_str(type));
}
static void check_clock(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(fmt[0] == 'C');
if (isalnum(fmt[1])) {
if (!strchr("nr", fmt[1]))
sm_warning("'%%pC' can only be followed by one of [nr]");
if (isalnum(fmt[2]))
sm_warning("'%%pC%c' cannot be followed by '%c'", fmt[1], fmt[2]);
}
if (!is_struct_tag(basetype, "clk"))
sm_error("'%%pC' expects argument of type 'struct clk*', argument %d has type '%s'",
vaidx, type_to_str(type));
}
static void va_format(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
assert(fmt[0] == 'V');
if (isalnum(fmt[1]))
sm_warning("%%pV cannot be followed by any alphanumerics");
if (!is_struct_tag(basetype, "va_format"))
sm_error("%%pV expects argument of type struct va_format*, argument %d has type '%s'", vaidx, type_to_str(type));
}
static void netdev_feature(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
static struct typedef_lookup netdev = { .name = "netdev_features_t" };
assert(fmt[0] == 'N');
if (fmt[1] != 'F') {
sm_error("%%pN must be followed by 'F'");
return;
}
if (isalnum(fmt[2]))
sm_warning("%%pNF cannot be followed by '%c'", fmt[2]);
typedef_lookup(&netdev);
if (!netdev.sym)
return;
if (basetype != netdev.sym)
sm_error("%%pNF expects argument of type netdev_features_t*, argument %d has type '%s'",
vaidx, type_to_str(type));
}
static void address_val(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
static struct typedef_lookup dma = { .name = "dma_addr_t" };
static struct typedef_lookup phys = { .name = "phys_addr_t" };
struct typedef_lookup *which = &phys;
const char *suf = "";
assert(fmt[0] == 'a');
if (isalnum(fmt[1])) {
switch (fmt[1]) {
case 'd':
which = &dma;
suf = "d";
break;
case 'p':
suf = "p";
break;
default:
sm_error("'%%pa' can only be followed by one of [dp]");
}
if (isalnum(fmt[2]))
sm_error("'%%pa%c' cannot be followed by '%c'", fmt[1], fmt[2]);
}
typedef_lookup(which);
if (!which->sym)
return;
if (basetype != which->sym) {
sm_error("'%%pa%s' expects argument of type '%s*', argument %d has type '%s'",
suf, which->name, vaidx, type_to_str(type));
}
}
static void block_device(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
const char *tag = "block_device";
assert(fmt[0] == 'g');
if (isalnum(fmt[1])) {
sm_warning("%%pg cannot be followed by '%c'", fmt[1]);
}
if (!is_struct_tag(basetype, tag))
sm_error("'%%p%c' expects argument of type struct '%s*', argument %d has type '%s'",
fmt[0], tag, vaidx, type_to_str(type));
}
static void flag_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
static struct typedef_lookup gfp = { .name = "gfp_t" };
assert(fmt[0] == 'G');
if (!isalnum(fmt[1])) {
sm_error("%%pG must be followed by one of [gpv]");
return;
}
switch (fmt[1]) {
case 'p':
case 'v':
if (basetype != &ulong_ctype)
sm_error("'%%pG%c' expects argument of type 'unsigned long *', argument %d has type '%s'",
fmt[1], vaidx, type_to_str(type));
break;
case 'g':
typedef_lookup(&gfp);
if (basetype != gfp.sym)
sm_error("'%%pGg' expects argument of type 'gfp_t *', argument %d has type '%s'",
vaidx, type_to_str(type));
break;
default:
sm_error("'%%pG' must be followed by one of [gpv]");
}
}
static void device_node_string(const char *fmt, struct symbol *type, struct symbol *basetype, int vaidx)
{
if (fmt[1] != 'F') {
sm_error("%%pO can only be followed by 'F'");
return;
}
if (!is_struct_tag(basetype, "device_node"))
sm_error("'%%pOF' expects argument of type 'struct device_node*', argument %d has type '%s'",
vaidx, type_to_str(type));
}
static void
pointer(const char *fmt, struct expression *arg, int vaidx)
{
struct symbol *type, *basetype;
type = get_type(arg);
if (!type) {
sm_warning("could not determine type of argument %d", vaidx);
return;
}
if (!is_ptr_type(type)) {
sm_error("%%p expects pointer argument, but argument %d has type '%s'",
vaidx, type_to_str(type));
return;
}
/* error pointers */
if (*fmt == 'e')
fmt++;
/* Just plain %p, nothing to check. */
if (!isalnum(*fmt))
return;
basetype = get_real_base_type(type);
if (is_void_type(basetype))
return;
/*
* Passing a pointer-to-array is harmless, but most likely one
* meant to pass pointer-to-first-element. If basetype is
* array type, we issue a notice and "dereference" the types
* once more.
*/
if (basetype->type == SYM_ARRAY) {
spam("note: passing pointer-to-array; is the address-of redundant?");
type = basetype;
basetype = get_real_base_type(type);
}
/*
* We pass both the type and the basetype to the helpers. If,
* for example, the pointer is really a decayed array which is
* passed to %pI4, we might want to check that it is in fact
* an array of four bytes. But most are probably only
* interested in whether the basetype makes sense. Also, the
* pointer may carry some annotation such as __user which
* might be worth checking in the handlers which actually
* dereference the pointer.
*/
switch (*fmt) {
case 'b':
case 'F':
case 'f':
case 'S':
case 's':
case 'B':
/* Can we do anything sensible? Check that the arg is a function pointer, for example? */
break;
case 'R':
case 'r':
resource_string(fmt, type, basetype, vaidx);
break;
case 'M':
case 'm':
mac_address_string(fmt, type, basetype, vaidx);
break;
case 'I':
case 'i':
switch (fmt[1]) {
case '4':
ip4(fmt, type, basetype, vaidx);
break;
case '6':
ip6(fmt, type, basetype, vaidx);
break;
case 'S':
ipS(fmt, type, basetype, vaidx);
break;
default:
sm_warning("'%%p%c' must be followed by one of [46S]", fmt[0]);
break;
}
break;
/*
* %pE and %ph can handle any valid pointer. We still check
* whether all the subsequent alphanumerics are valid for the
* particular %pX conversion.
*/
case 'E':
escaped_string(fmt, type, basetype, vaidx);
break;
case 'h':
hex_string(fmt, type, basetype, vaidx);
break;
case 'U': /* TODO */
break;
case 'V':
va_format(fmt, type, basetype, vaidx);
break;
case 'K': /* TODO */
break;
case 'N':
netdev_feature(fmt, type, basetype, vaidx);
break;
case 'a':
address_val(fmt, type, basetype, vaidx);
break;
case 'D':
case 'd':
dentry_file(fmt, type, basetype, vaidx);
break;
case 't':
time_and_date(fmt, type, basetype, vaidx);
break;
case 'C':
check_clock(fmt, type, basetype, vaidx);
break;
case 'g':
block_device(fmt, type, basetype, vaidx);
break;
case 'G':
flag_string(fmt, type, basetype, vaidx);
break;
case 'O':
device_node_string(fmt, type, basetype, vaidx);
break;
case 'x':
/* 'x' is for an unhashed pointer */
break;
case '4':
if (strncmp(fmt, "4cc", 3) != 0)
sm_warning("unrecognized format '%%p4%c'. Was '%%p4cc' intended?", fmt[1]);
break;
default:
sm_error("unrecognized %%p extension '%c', treated as normal %%p", *fmt);
}
}
/*
* A common error is to pass a "char" or "signed char" to %02x (or
* %.2X or some other variant). This can actually be a security
* problem, because a lot of code expects this to produce exactly two
* characters of output. Unfortunately this also produces false
* positives, since we're sometimes in arch-specific code on an arch
* where char is always unsigned.
*/
static void
hexbyte(const char *fmt, int fmt_len, struct expression *arg, int vaidx, struct printf_spec spec)
{
struct symbol *type;
/*
* For now, just check the most common and obvious, which is
* roughly %[.0]2[xX].
*/
if (spec.field_width != 2 && spec.precision != 2)
return;
if (spec.base != 16)
return;
type = get_type(arg);
if (!type) {
sm_warning("could not determine type of argument %d", vaidx);
return;
}
if (type == &char_ctype || type == &schar_ctype)
sm_warning("argument %d to %.*s specifier has type '%s'",
vaidx, fmt_len, fmt, type_to_str(type));
}
static int
check_format_string(const char *fmt, const char *caller)
{
const char *f;
for (f = fmt; *f; ++f) {
unsigned char c = *f;
switch (c) {
case KERN_SOH_ASCII:
/*
* This typically arises from bad conversion
* to pr_*, e.g. pr_warn(KERN_WARNING "something").
*/
if (f != fmt)
sm_warning("KERN_* level not at start of string");
/*
* In a very few cases, the level is actually
* computed and passed via %c, as in KERN_SOH
* "%c...". printk explicitly supports
* this.
*/
if (!(('0' <= f[1] && f[1] <= '7') ||
f[1] == 'd' || /* KERN_DEFAULT */
f[1] == 'c' || /* KERN_CONT */
(f[1] == '%' && f[2] == 'c')))
sm_warning("invalid KERN_* level: KERN_SOH_ASCII followed by '\\x%02x'", (unsigned char)f[1]);
break;
case '\t':
case '\n':
case '\r':
case 0x20 ... 0x7e:
break;
case 0x80 ... 0xff:
sm_warning("format string contains non-ascii character '\\x%02x'", c);
break;
case 0x08:
if (f == fmt)
break;
/* fall through */
default:
sm_warning("format string contains unusual character '\\x%02x'", c);
break;
}
}
f = strstr(fmt, caller);
if (f && strstr(f+1, caller))
sm_warning("format string contains name of enclosing function '%s' twice", caller);
return f != NULL;
}
static int arg_is___func__(struct expression *arg)
{
if (arg->type != EXPR_SYMBOL)
return 0;
return !strcmp(arg->symbol_name->name, "__func__") ||
!strcmp(arg->symbol_name->name, "__FUNCTION__") ||
!strcmp(arg->symbol_name->name, "__PRETTY_FUNCTION__");
}
static int arg_contains_caller(struct expression *arg, const char *caller)
{
if (arg->type != EXPR_STRING)
return 0;
return strstr(arg->string->data, caller) != NULL;
}
static int is_array_of_const_char(struct symbol *sym)
{
struct symbol *base = sym->ctype.base_type;
if (base->type != SYM_ARRAY)
return 0;
if (!(base->ctype.modifiers & MOD_CONST))
return 0;
if (!is_char_type(base->ctype.base_type)) {
spam("weird: format argument is array of const '%s'", type_to_str(base->ctype.base_type));
return 0;
}
return 1;
}
static int is_const_pointer_to_const_char(struct symbol *sym)
{
struct symbol *base = sym->ctype.base_type;
if (!(sym->ctype.modifiers & MOD_CONST))
return 0;
if (base->type != SYM_PTR)
return 0;
if (!(base->ctype.modifiers & MOD_CONST))
return 0;
if (!is_char_type(base->ctype.base_type)) {
spam("weird: format argument is pointer to const '%s'", type_to_str(base->ctype.base_type));
return 0;
}
return 1;
}
static int unknown_format(struct expression *expr)
{
struct state_list *slist;
slist = get_strings(expr);
if (!slist)
return 1;
if (slist_has_state(slist, &undefined))
return 1;
free_slist(&slist);
return 0;
}
static bool has_hex_prefix(const char *orig_fmt, const char *old_fmt)
{
return old_fmt >= orig_fmt + 2 &&
old_fmt[-2] == '0' && _tolower(old_fmt[-1]) == 'x';
}
static bool is_integer_specifier(int type)
{
switch (type) {
case FORMAT_TYPE_LONG_LONG:
case FORMAT_TYPE_ULONG:
case FORMAT_TYPE_LONG:
case FORMAT_TYPE_UBYTE:
case FORMAT_TYPE_BYTE:
case FORMAT_TYPE_USHORT:
case FORMAT_TYPE_SHORT:
case FORMAT_TYPE_UINT:
case FORMAT_TYPE_INT:
case FORMAT_TYPE_SIZE_T:
case FORMAT_TYPE_PTRDIFF:
return true;
default:
return false;
}
}
static int
is_cast_expr(struct expression *expr)
{
if (!expr)
return 0;
switch (expr->type) {
case EXPR_CAST:
case EXPR_FORCE_CAST:
/* not EXPR_IMPLIED_CAST for our purposes */
return 1;
default:
return 0;
}
}
static void
check_cast_from_pointer(const char *fmt, int len, struct expression *arg, int va_idx)
{
/*
* This can easily be fooled by passing 0+(long)ptr or doing
* "long local_var = (long)ptr" and passing local_var to
* %lx. Tough.
*/
if (!is_cast_expr(arg))
return;
while (is_cast_expr(arg))
arg = arg->cast_expression;
if (is_ptr_type(get_final_type(arg)))
sm_warning("argument %d to %.*s specifier is cast from pointer",