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Boost _ Firedancer v0.1 33669 - [Blockchain_DLT - Medium] fd_quic_process_packet out of bounds read.md

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fd_quic_process_packet out of bounds read

Submitted on Fri Jul 26 2024 00:53:15 GMT-0400 (Atlantic Standard Time) by @gln for Boost | Firedancer v0.1

Report ID: #33669

Report type: Blockchain/DLT

Report severity: Medium

Target: https://github.com/firedancer-io/firedancer/tree/e60d9a6206efaceac65a5a2c3a9e387a79d1d096

Impacts:

  • Process to process RCE between sandboxed tiles

Description

Brief/Intro

QUIC tile fails to validate data received from Net tile.

If udp packet length is too short, out of bounds read might be triggered.

Vulnerability Details

Lets look at the code https://github.com/firedancer-io/firedancer/blob/main/src/waltz/quic/fd_quic.c#L2782


void
fd_quic_process_packet( fd_quic_t * quic,
                        uchar *     data,
                        ulong       data_sz ) {

  fd_quic_state_t * state = fd_quic_get_state( quic );

  ulong rc = 0;

  /* holds the remainder of the packet*/
  uchar * cur_ptr = data;
  ulong   cur_sz  = data_sz;

  if( FD_UNLIKELY( data_sz > 0xffffu ) ) {
    /* sanity check */
    return;
  }

  fd_quic_pkt_t pkt = { .datagram_sz = (uint)data_sz };

  pkt.rcv_time = state->now;

  rc = fd_quic_decode_eth( pkt.eth, cur_ptr, cur_sz );
  if( FD_UNLIKELY( rc == FD_QUIC_PARSE_FAIL ) ) {
    /* TODO count failure, log-debug failure */
    return;
  }

  if( FD_UNLIKELY( pkt.eth->net_type != FD_ETH_HDR_TYPE_IP ) ) {
    FD_DEBUG( FD_LOG_DEBUG(( "Invalid ethertype: %4.4x", pkt.eth->net_type )) );
    return;
  }

  cur_ptr += rc;
  cur_sz  -= rc;

  rc = fd_quic_decode_ip4( pkt.ip4, cur_ptr, cur_sz );
  if( FD_UNLIKELY( rc == FD_QUIC_PARSE_FAIL ) ) {
    /* TODO count failure, log-debug failure */
    return;
  }

  if( FD_UNLIKELY( pkt.ip4->protocol != FD_IP4_HDR_PROTOCOL_UDP ) ) {
    return;
  }

  if( FD_UNLIKELY( pkt.ip4->net_tot_len > cur_sz ) ) {
    return;
  }

  cur_ptr += rc;
  cur_sz  -= rc;

1.  rc = fd_quic_decode_udp( pkt.udp, cur_ptr, cur_sz );
  if( FD_UNLIKELY( rc == FD_QUIC_PARSE_FAIL ) ) {
    return;
  }

  if( FD_UNLIKELY( pkt.udp->net_len > cur_sz ) ) {
    return;
  }

  cur_ptr += rc;
2.  cur_sz   = pkt.udp->net_len - rc; 
  ...

  int long_pkt = !!( (uint)cur_ptr[0] & 0x80u );

  uint version = 0;

  if( long_pkt ) {
    version = DECODE_UINT32( cur_ptr + 1 );

    ...

3.  while(1) {
      if( FD_UNLIKELY( cur_sz < FD_QUIC_SHORTEST_PKT ) ) return;

      int short_pkt = !( (uint)cur_ptr[0] & 0x80u );

      if( FD_UNLIKELY( short_pkt ) ) break;

      uint cur_version = DECODE_UINT32( cur_ptr + 1 );
      ...
      ...

  1. Note that fd_quic_decode_udp() returns 8 (size of udp header)

  2. If pkt.udp->net_len is less than 8, cur_sz will be set to a negative value (large positive)

  3. while loop will go out of bounds when trying to read quic packets

Impact Details

Might be possible to leak parts of memory from QUIC tile.

Denial of service is possible as well.

Proof of concept

Proof of Concept

Most simple way to reproduce this issue is to use fuzz_quic_wire fuzzer with memory sanitizer.

How to reproduce:

  1. build fuzz tests with memory sanitizer, edit config/extra/with-asan.mk and change variables to:
CPPFLAGS+=-fsanitize=memory

LDFLAGS+=-fsanitize=memory
  1. build with command:

EXTRAS="asan fuzz" make -j fuzz-test

  1. get proof of concept by using provided gist link

  2. unpack and decode it:

$ base64 -d test.txt > test.bin
  1. run fuzz_quic_wire test:
$ ./fuzz_quic_wire test.bin


Running: test.bin
==325630==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5fc853ce6dae in fd_quic_process_packet /src/waltz/quic/fd_quic.c:2889:7
    #1 0x5fc853cbc939 in send_udp_packet /src/waltz/quic/tests/fuzz_quic_wire.c:97:3
    #2 0x5fc853cbc939 in LLVMFuzzerTestOneInput /src/waltz/quic/tests/fuzz_quic_wire.c:189:3
    #3 0x5fc853c1a553 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (/build/linux/clang/x86_64/fuzz-test/fuzz_quic_wire/fuzz_quic_wire+0x80553) (BuildId: dbb992a413a9e6c41b1271a0480fad6bf3051f9f)
    #4 0x5fc853c042cf in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) (/build/linux/clang/x86_64/fuzz-test/fuzz_quic_wire/fuzz_quic_wire+0x6a2cf) (BuildId: dbb992a413a9e6c41b1271a0480fad6bf3051f9f)
    #5 0x5fc853c0a026 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (/build/linux/clang/x86_64/fuzz-test/fuzz_quic_wire/fuzz_quic_wire+0x70026) (BuildId: dbb992a413a9e6c41b1271a0480fad6bf3051f9f)
    #6 0x5fc853c33e42 in main (/build/linux/clang/x86_64/fuzz-test/fuzz_quic_wire/fuzz_quic_wire+0x99e42) (BuildId: dbb992a413a9e6c41b1271a0480fad6bf3051f9f)
    #7 0x7e7a43629d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #8 0x7e7a43629e3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #9 0x5fc853bfeb94 in _start (/build/linux/clang/x86_64/fuzz-test/fuzz_quic_wire/fuzz_quic_wire+0x64b94) (BuildId: dbb992a413a9e6c41b1271a0480fad6bf3051f9f)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /src/waltz/quic/fd_quic.c:2889:7 in fd_quic_process_packet