How to build wasmtime with wmemcheck support?

[trcrsired]

I build wasmtime with this command and still it does not find --wmemcheck why?

$ cargo build --features wmemcheck --release

wasmtime run --wmemcheck hello
error: unexpected argument '--wmemcheck' found

  tip: to pass '--wmemcheck' as a value, use '-- --wmemcheck'

Usage: wasmtime run [OPTIONS] <WASM>...

For more information, try '--help'

[bjorn3]

You need -W wmemcheck=y/--wasm wmemcheck=y. Looks like the docs didn't get changed when the cli options got changed a while back.

[trcrsired]

You need -W wmemcheck=y/--wasm wmemcheck=y. Looks like the docs didn't get changed when the cli options got changed a while back.

#include<fcntl.h>
#include<unistd.h>

int main()
{
 int fd = open("example.txt", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
}

$ wasmtime --wasm wmemcheck=y --dir . ./test.wasm 
Error: failed to run main module `./test.wasm`

Caused by:
    0: failed to invoke command default
    1: error while executing at wasm backtrace:
           0:  0xb3e - test.wasm!dlmalloc
           1: 0x232b - test.wasm!calloc
           2: 0x2537 - test.wasm!internal_register_preopened_fd_unlocked
           3: 0x24ac - test.wasm!__wasilibc_populate_preopens
           4: 0x266d - test.wasm!__wasilibc_find_abspath
           5: 0x264a - test.wasm!__wasilibc_find_relpath
           6: 0x23ae - test.wasm!open
           7: 0x2f09 - test.wasm!__main_void
           8:  0x1a7 - test.wasm!_start
    2: Invalid store at addr 0x1066c of size 4

calloc does not work right?

[cfallin]

It looks like wmemcheck's heuristic for finding malloc and avoiding instrumenting stores within the malloc implementation itself is no longer valid -- here the implementation looks for functions named malloc and free, but at some point wasi-libc must have renamed malloc to dlmalloc.

You're welcome to submit a PR to accept both options. Note that wmemcheck is described in the documentation as experimental and unfinished -- we had an intern build it last year and it was an excellent start but it needs a little more polish before we mark the option as "polished" and included in default builds. For example (to save you the trouble of filing another bug report!), it also doesn't support realloc currently.

[trcrsired]

It looks like wmemcheck's heuristic for finding malloc and avoiding instrumenting stores within the malloc implementation itself is no longer valid -- here the implementation looks for functions named malloc and free, but at some point wasi-libc must have renamed malloc to dlmalloc.

You're welcome to submit a PR to accept both options. Note that wmemcheck is described in the documentation as experimental and unfinished -- we had an intern build it last year and it was an excellent start but it needs a little more polish before we mark the option as "polished" and included in default builds. For example (to save you the trouble of filing another bug report!), it also doesn't support realloc currently.

So the implementation is still ongoing and far from usable at this point right? And if the symbols got stripped, it cannot detect issues either right since now the wasmtime cannot find malloc and calloc

[cfallin]

That's correct.