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l2cap: check SDU len against provided buffer, prevent buffer overrun during reassembly

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This commit is contained in:
Matthias Ringwald 2017-09-18 13:52:45 +02:00
parent e9cfb251d0
commit bb98c113be
1 changed files with 7 additions and 2 deletions
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9
src/l2cap.c
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@ -3083,12 +3083,17 @@ static void l2cap_acl_le_handler(hci_con_handle_t handle, uint8_t *packet, uint1
// first fragment
uint16_t pos = 0;
if (!l2cap_channel->receive_sdu_len){
l2cap_channel->receive_sdu_len = little_endian_read_16(packet, COMPLETE_L2CAP_HEADER);
uint16_t sdu_len = little_endian_read_16(packet, COMPLETE_L2CAP_HEADER);
if(sdu_len > l2cap_channel->local_mtu) break; // SDU would be larger than our buffer
l2cap_channel->receive_sdu_len = sdu_len;
l2cap_channel->receive_sdu_pos = 0;
pos += 2;
size -= 2;
}
memcpy(&l2cap_channel->receive_sdu_buffer[l2cap_channel->receive_sdu_pos], &packet[COMPLETE_L2CAP_HEADER+pos], size-COMPLETE_L2CAP_HEADER);
uint16_t fragment_size = size-COMPLETE_L2CAP_HEADER;
uint16_t remaining_space = l2cap_channel->local_mtu - l2cap_channel->receive_sdu_pos;
if (fragment_size > remaining_space) break; // SDU would cause buffer overrun
memcpy(&l2cap_channel->receive_sdu_buffer[l2cap_channel->receive_sdu_pos], &packet[COMPLETE_L2CAP_HEADER+pos], fragment_size);
l2cap_channel->receive_sdu_pos += size - COMPLETE_L2CAP_HEADER;
// done?
log_info("le packet pos %u, len %u", l2cap_channel->receive_sdu_pos, l2cap_channel->receive_sdu_len);