rbpf_cli hangs loading a shared library file

[vakond]

This command:

rbpf_cli --use disassembler --elf spl_token-3.1.0.so

takes forever to complete with CPU usage = 100%.

The latest rbpf main branch had been used. The input file's location: https://github.com/solana-labs/solana/blob/master/program-test/src/programs/spl_token-3.1.0.so

[vakond]

One can attach a debugger and see the program spends time searching something. Looks like it entered a forever loop.

* thread #1, name = 'rbpf_cli', stop reason = signal SIGSTOP
    frame #0: 0x000055c2b033011c rbpf_cli`alloc::collections::btree::search::_$LT$impl$u20$alloc..collections..btree..node..NodeRef$LT$BorrowType$C$K$C$V$C$Type$GT$$GT$::find_key_index::h6a386a2ad93b0899(self=0x00007ffe74b82f10, key=0x00007ffe74b83308) at search.rs:206:17
   203          let keys = node.keys();
   204          for (i, k) in keys.iter().enumerate() {
   205              match key.cmp(k.borrow()) {
-> 206                  Ordering::Greater => {}
   207                  Ordering::Equal => return IndexResult::KV(i),
   208                  Ordering::Less => return IndexResult::Edge(i),
   209              }

Executable module set to "target/debug/rbpf_cli".
Architecture set to: x86_64-pc-linux-gnu.

[vakond]

rustup show

Default host: x86_64-unknown-linux-gnu

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu (default)
bpf

active toolchain
----------------

stable-x86_64-unknown-linux-gnu (default)
rustc 1.52.1 (9bc8c42bb 2021-05-09)

[Lichtso]

Thanks for the detailed bug report!

It was indeed an infinite loop caused by an impossible CFG. Which in turn was caused by a leading unreachable exit instruction at the beginning of the program, shifting all basic blocks of the first function by one.