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Merge pull request #11202 from s-hadinger/crash_protection 

Add crash protection to ext_vsnprintf_P
This commit is contained in:
s-hadinger 2021-03-02 22:11:11 +01:00 committed by GitHub
parent 2e7cf79111 38e83113bb
commit 0ea89b2ed6
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 51 additions and 38 deletions
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89
lib/default/Ext-printf/src/ext_printf.cpp
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@ -212,6 +212,9 @@ char * copyStr(const char * str) {
return cpy;
}
const char ext_invalid_mem[] PROGMEM = "<--INVALID-->";
const uint32_t min_valid_ptr = 0x3FF00000; // addresses below this line are invalid
int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list va) {
va_list va_cpy;
va_copy(va_cpy, va);
@ -222,7 +225,7 @@ int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list
char * fmt = fmt_cpy;
const uint32_t ALLOC_SIZE = 12;
static char * allocs[ALLOC_SIZE] = {}; // initialized to zeroes
static const char * allocs[ALLOC_SIZE] = {}; // initialized to zeroes
uint32_t alloc_idx = 0;
static char hex[20]; // buffer used for 64 bits, favor RAM instead of stack to remove pressure
@ -264,12 +267,13 @@ int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list
fmt++;
uint32_t cur_val = va_arg(va, uint32_t); // current value
const char ** cur_val_ptr = va_cur_ptr4(va, const char*); // pointer to value on stack
char * new_val_str = (char*) "";
const char * new_val_str = "";
switch (*fmt) {
case 'H': // Hex, decimals indicates the length, default 2
{
if (decimals < 0) { decimals = 0; }
if (decimals > 0) {
if (cur_val < min_valid_ptr) { new_val_str = ext_invalid_mem; }
else if (decimals > 0) {
char * hex_char = (char*) malloc(decimals*2 + 2);
ToHex_P((const uint8_t *)cur_val, decimals, hex_char, decimals*2 + 2);
new_val_str = hex_char;
@ -280,13 +284,16 @@ int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list
break;
case 'B': // Pointer to SBuffer
{
const SBuffer & buf = *(const SBuffer*)cur_val;
size_t buf_len = (&buf != nullptr) ? buf.len() : 0;
if (buf_len) {
char * hex_char = (char*) malloc(buf_len*2 + 2);
ToHex_P(buf.getBuffer(), buf_len, hex_char, buf_len*2 + 2);
new_val_str = hex_char;
allocs[alloc_idx++] = new_val_str;
if (cur_val < min_valid_ptr) { new_val_str = ext_invalid_mem; }
else {
const SBuffer & buf = *(const SBuffer*)cur_val;
size_t buf_len = (&buf != nullptr) ? buf.len() : 0;
if (buf_len) {
char * hex_char = (char*) malloc(buf_len*2 + 2);
ToHex_P(buf.getBuffer(), buf_len, hex_char, buf_len*2 + 2);
new_val_str = hex_char;
allocs[alloc_idx++] = new_val_str;
}
}
}
break;
@ -315,40 +322,46 @@ int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list
// Note: float MUST be passed by address, because C alsays promoted float to double when in vararg
case 'f': // input is `float`, printed to float with 2 decimals
{
bool truncate = false;
if (decimals < 0) {
decimals = -decimals;
truncate = true;
}
float number = *(float*)cur_val;
if (isnan(number) || isinf(number)) {
new_val_str = (char*) "null";
} else {
dtostrf(*(float*)cur_val, (decimals + 2), decimals, hex);
if (truncate) {
uint32_t last = strlen(hex) - 1;
// remove trailing zeros
while (hex[last] == '0') {
hex[last--] = 0; // remove last char
}
// remove trailing dot
if (hex[last] == '.') {
hex[last] = 0;
}
if (cur_val < min_valid_ptr) { new_val_str = ext_invalid_mem; }
else {
bool truncate = false;
if (decimals < 0) {
decimals = -decimals;
truncate = true;
}
float number = *(float*)cur_val;
if (isnan(number) || isinf(number)) {
new_val_str = "null";
} else {
dtostrf(*(float*)cur_val, (decimals + 2), decimals, hex);
if (truncate) {
uint32_t last = strlen(hex) - 1;
// remove trailing zeros
while (hex[last] == '0') {
hex[last--] = 0; // remove last char
}
// remove trailing dot
if (hex[last] == '.') {
hex[last] = 0;
}
}
new_val_str = copyStr(hex);
allocs[alloc_idx++] = new_val_str;
}
new_val_str = copyStr(hex);
allocs[alloc_idx++] = new_val_str;
}
}
break;
// '%_X' outputs a 64 bits unsigned int to uppercase HEX with 16 digits
case 'X': // input is `uint64_t*`, printed as 16 hex digits (no prefix 0x)
{
if ((decimals < 0) || (decimals > 16)) { decimals = 16; }
U64toHex(*(uint64_t*)cur_val, hex, decimals);
new_val_str = copyStr(hex);
allocs[alloc_idx++] = new_val_str;
if (cur_val < min_valid_ptr) { new_val_str = ext_invalid_mem; }
else {
if ((decimals < 0) || (decimals > 16)) { decimals = 16; }
U64toHex(*(uint64_t*)cur_val, hex, decimals);
new_val_str = copyStr(hex);
allocs[alloc_idx++] = new_val_str;
}
}
break;
// Trying to do String allocation alternatives, but not as interesting as I thought in the beginning
@ -382,7 +395,7 @@ int32_t ext_vsnprintf_P(char * buf, size_t buf_len, const char * fmt_P, va_list
// disallocated all temporary strings
for (uint32_t i = 0; i < alloc_idx; i++) {
free(allocs[i]); // it is ok to call free() on nullptr so we don't test for nullptr first
free((void*)allocs[i]); // it is ok to call free() on nullptr so we don't test for nullptr first
allocs[i] = nullptr;
}
free(fmt_cpy); // free the local copy of the format string