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Apply proposed changes to fix RAR VMSF_DELTA Filter Signedness error (CVE-2012-6706)
Cherry picked from commit a7d8447bd9a4d5ae1fa970c1849c8caeb5f1a805 [Link 1] and
d4699442bce76574573dc564e7f2177d679b88bd [Link 2].
Link 1: https://github.com/Cisco-Talos/clamav-devel/commit/a7d8447bd9a4d5ae1fa970c1849c8caeb5f1a805
Link 2: https://github.com/Cisco-Talos/clamav-devel/commit/d4699442bce76574573dc564e7f2177d679b88bd
--- a/libclamunrar/unrarvm.c
+++ b/libclamunrar/unrarvm.c
@@ -213,17 +213,20 @@ void rarvm_addbits(rarvm_input_t *rarvm_input, int bits)
unsigned int rarvm_getbits(rarvm_input_t *rarvm_input)
{
- unsigned int bit_field;
+ unsigned int bit_field = 0;
- if (rarvm_input->in_addr+2 < rarvm_input->buf_size) {
+ if (rarvm_input->in_addr < rarvm_input->buf_size) {
bit_field = (unsigned int) rarvm_input->in_buf[rarvm_input->in_addr] << 16;
- bit_field |= (unsigned int) rarvm_input->in_buf[rarvm_input->in_addr+1] << 8;
- bit_field |= (unsigned int) rarvm_input->in_buf[rarvm_input->in_addr+2];
- bit_field >>= (8-rarvm_input->in_bit);
-
- return (bit_field & 0xffff);
+ if (rarvm_input->in_addr+1 < rarvm_input->buf_size) {
+ bit_field |= (unsigned int) rarvm_input->in_buf[rarvm_input->in_addr+1] << 8;
+ if (rarvm_input->in_addr+2 < rarvm_input->buf_size) {
+ bit_field |= (unsigned int) rarvm_input->in_buf[rarvm_input->in_addr+2];
+ }
+ }
}
- return 0;
+ bit_field >>= (8-rarvm_input->in_bit);
+
+ return (bit_field & 0xffff);
}
unsigned int rarvm_read_data(rarvm_input_t *rarvm_input)
@@ -311,10 +314,10 @@ static unsigned int *rarvm_get_operand(rarvm_data_t *rarvm_data,
}
}
-static unsigned int filter_itanium_getbits(unsigned char *data, int bit_pos, int bit_count)
+static unsigned int filter_itanium_getbits(unsigned char *data, unsigned int bit_pos, unsigned int bit_count)
{
- int in_addr=bit_pos/8;
- int in_bit=bit_pos&7;
+ unsigned int in_addr=bit_pos/8;
+ unsigned int in_bit=bit_pos&7;
unsigned int bit_field=(unsigned int)data[in_addr++];
bit_field|=(unsigned int)data[in_addr++] << 8;
bit_field|=(unsigned int)data[in_addr++] << 16;
@@ -323,10 +326,10 @@ static unsigned int filter_itanium_getbits(unsigned char *data, int bit_pos, int
return(bit_field & (0xffffffff>>(32-bit_count)));
}
-static void filter_itanium_setbits(unsigned char *data, unsigned int bit_field, int bit_pos, int bit_count)
+static void filter_itanium_setbits(unsigned char *data, unsigned int bit_field, unsigned int bit_pos, unsigned int bit_count)
{
- int i, in_addr=bit_pos/8;
- int in_bit=bit_pos&7;
+ unsigned int i, in_addr=bit_pos/8;
+ unsigned int in_bit=bit_pos&7;
unsigned int and_mask=0xffffffff>>(32-bit_count);
and_mask=~(and_mask<<in_bit);
@@ -343,11 +346,12 @@ static void filter_itanium_setbits(unsigned char *data, unsigned int bit_field,
static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_filters_t filter_type)
{
unsigned char *data, cmp_byte2, cur_byte, *src_data, *dest_data;
- int i, j, data_size, channels, src_pos, dest_pos, border, width, PosR;
- int op_type, cur_channel, byte_count, start_pos, pa, pb, pc;
+ unsigned int i, j, data_size, channels, src_pos, dest_pos, border, width, PosR;
+ unsigned int op_type, cur_channel, byte_count, start_pos;
+ int pa, pb, pc;
unsigned int file_offset, cur_pos, predicted;
- int32_t offset, addr;
- const int file_size=0x1000000;
+ uint32_t offset, addr;
+ const unsigned int file_size=0x1000000;
switch(filter_type) {
case VMSF_E8:
@@ -356,7 +360,7 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
data_size = rarvm_data->R[4];
file_offset = rarvm_data->R[6];
- if (((unsigned int)data_size >= VM_GLOBALMEMADDR) || (data_size < 4)) {
+ if ((data_size > VM_GLOBALMEMADDR) || (data_size < 4)) {
break;
}
@@ -367,12 +371,14 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
if (cur_byte==0xe8 || cur_byte==cmp_byte2) {
offset = cur_pos+file_offset;
addr = GET_VALUE(FALSE, data);
- if (addr < 0) {
- if (addr+offset >=0 ) {
+ // We check 0x80000000 bit instead of '< 0' comparison
+ // not assuming int32 presence or uint size and endianness.
+ if ((addr & 0x80000000)!=0) { // addr<0
+ if (((addr+offset) & 0x80000000)==0) { // addr+offset>=0
SET_VALUE(FALSE, data, addr+file_size);
}
} else {
- if (addr<file_size) {
+ if (((addr-file_size) & 0x80000000)!=0) { // addr<file_size
SET_VALUE(FALSE, data, addr-offset);
}
}
@@ -386,7 +392,7 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
data_size = rarvm_data->R[4];
file_offset = rarvm_data->R[6];
- if (((unsigned int)data_size >= VM_GLOBALMEMADDR) || (data_size < 21)) {
+ if ((data_size > VM_GLOBALMEMADDR) || (data_size < 21)) {
break;
}
@@ -429,7 +435,7 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
border = data_size*2;
SET_VALUE(FALSE, &rarvm_data->mem[VM_GLOBALMEMADDR+0x20], data_size);
- if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2) {
+ if (data_size > VM_GLOBALMEMADDR/2 || channels > 1024 || channels == 0) {
break;
}
for (cur_channel=0 ; cur_channel < channels ; cur_channel++) {
@@ -440,7 +446,7 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
}
break;
case VMSF_RGB: {
- const int channels=3;
+ const unsigned int channels=3;
data_size = rarvm_data->R[4];
width = rarvm_data->R[0] - 3;
PosR = rarvm_data->R[1];
@@ -448,15 +454,14 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
dest_data = src_data + data_size;
SET_VALUE(FALSE, &rarvm_data->mem[VM_GLOBALMEMADDR+0x20], data_size);
- if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2) {
+ if (data_size > VM_GLOBALMEMADDR/2 || data_size < 3 || width > data_size || PosR > 2) {
break;
}
for (cur_channel=0 ; cur_channel < channels; cur_channel++) {
unsigned int prev_byte = 0;
for (i=cur_channel ; i<data_size ; i+=channels) {
- int upper_pos=i-width;
- if (upper_pos >= 3) {
- unsigned char *upper_data = dest_data+upper_pos;
+ if (i >= width+3) {
+ unsigned char *upper_data = dest_data+i-width;
unsigned int upper_byte = *upper_data;
unsigned int upper_left_byte = *(upper_data-3);
predicted = prev_byte+upper_byte-upper_left_byte;
@@ -486,13 +491,14 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
break;
}
case VMSF_AUDIO: {
- int channels=rarvm_data->R[0];
+ unsigned int channels=rarvm_data->R[0];
data_size = rarvm_data->R[4];
src_data = rarvm_data->mem;
dest_data = src_data + data_size;
SET_VALUE(FALSE, &rarvm_data->mem[VM_GLOBALMEMADDR+0x20], data_size);
- if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2) {
+ // In fact, audio channels never exceed 4.
+ if (data_size > VM_GLOBALMEMADDR/2 || channels > 128 || channels == 0) {
break;
}
for (cur_channel=0 ; cur_channel < channels ; cur_channel++) {
@@ -553,7 +559,7 @@ static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_fil
data_size = rarvm_data->R[4];
src_pos = 0;
dest_pos = data_size;
- if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2) {
+ if (data_size > VM_GLOBALMEMADDR/2) {
break;
}
while (src_pos < data_size) {
--
2.16.2
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