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Another bounds check for palmdoc decompress

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Kovid Goyal 2023-06-08 14:56:25 +05:30
parent c0f2581f55
commit faf096384b
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GPG Key ID: 06BC317B515ACE7C
1 changed files with 10 additions and 6 deletions
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12
src/calibre/ebooks/compression/palmdoc.c
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@ -43,7 +43,7 @@ typedef struct {
#define CHAR(x) (( (x) > 127 ) ? (x)-256 : (x))
static bool
write_to_bytes_object(PyObject **output, Py_ssize_t pos, char ch) {
write_to_bytes_object(PyObject **output, size_t pos, char ch) {
if (pos >= PyBytes_GET_SIZE(*output)) {
if (_PyBytes_Resize(output, 2 * pos) != 0) return false;
}
@ -54,15 +54,17 @@ write_to_bytes_object(PyObject **output, Py_ssize_t pos, char ch) {
static PyObject *
cpalmdoc_decompress(PyObject *self, PyObject *args) {
const char *_input = NULL; Py_ssize_t input_len = 0;
Byte *input; Byte c; PyObject *ans;
Py_ssize_t i = 0, o = 0, j = 0, di, n;
Byte *input; Byte c; PyObject *ans = NULL;
Py_ssize_t i = 0, j = 0;
size_t o = 0, di = 0, n = 0;
if (!PyArg_ParseTuple(args, "y#", &_input, &input_len))
return NULL;
input = (Byte *) PyMem_Malloc(sizeof(Byte)*input_len);
if (input == NULL) return PyErr_NoMemory();
// Map chars to bytes
for (j = 0; j < input_len; j++)
for (j = 0; j < input_len; j++) {
input[j] = (_input[j] < 0) ? _input[j]+256 : _input[j];
}
ans = PyBytes_FromStringAndSize(NULL, 8*input_len);
if (ans == NULL) { PyMem_Free(input); return NULL; }
@ -78,11 +80,13 @@ cpalmdoc_decompress(PyObject *self, PyObject *args) {
} else if (i < input_len) { // 80-BF repeat sequences
c = (c << 8) + input[i++];
di = (c & 0x3FFF) >> 3;
if (di <= o) {
for ( n = (c & 7) + 3; n--; ++o ) {
if (!write_to_bytes_object(&ans, o, PyBytes_AS_STRING(ans)[o-di])) { PyMem_Free(input); return NULL; }
}
}
}
}
#undef write
PyMem_Free(input);
if (_PyBytes_Resize(&ans, o) != 0) return NULL;