Dmitry Vyukov

> His prototype: It turns out to be not that easy. LineReader has info about inlined frames, but only file:line, not the function name. And we need inline function names...

LineEntry has Column field: https://pkg.go.dev/debug/[email protected]#LineEntry

Maybe we could map coverage and execution time to some logarithmic buckets: 1, 10, 100, or finer-grained 1,2,5,10,20,50,100...? Also amount of coverage may be very different for different syscalls, some...

> Some features (1) require a one-time setup, other features (2) are passed via `ipc.EnvFlags` and we must set them up on every `syz-executor` restart. In `syz-fuzzer` (actually, mostly in...

> Another, probably even easier, approach could be to just add some (skip) Or more generally: a function that transforms a program into a "safe" version. We already have something...

Hi Alessandro, Features are not returned as nil when debugfs is not mounted, the only case I see where we return nil features is this: https://github.com/google/syzkaller/blob/610f2a54d02f8cf4f2454c03bf679b602e6e59b6/pkg/host/features.go#L89 Are you trying to...

Yes, use of KCOV requires DEBUGFS, but syzkaller shouldn't crash if DEBUGFS is not mounted. I see, we get nil r.Features if we get here: https://github.com/google/syzkaller/blob/610f2a54d02f8cf4f2454c03bf679b602e6e59b6/syz-fuzzer/fuzzer.go#L154 and it crashes when...

Whatever you prefer. A fix that prevents r.Features from being nil in the first place looks reasonable to merge.

If you want better error message, then it should be done here: https://github.com/google/syzkaller/blob/69f2eab004cdc5bce339d5359dcf234698153dc7/pkg/host/features_linux.go#L45-L56 I see it already checks for debugfs, so perhaps this function needs improvement: https://github.com/google/syzkaller/blob/69f2eab004cdc5bce339d5359dcf234698153dc7/pkg/host/features_linux.go#L246-L251 Using `if suppFeatures...

> In the meantime, I've rewritten the checkDebugFS() function to make it more robust, if you consider this worthy, I can open another PR for this. As I mentioned this...