core: Panic on login

[davecgh]

I'm getting a panic on login with the master branch at commit 0030e49e0aa4159f2b55eee546c9083a51146c1e.

Prior to this, I started the MM bots and it crashed shortly after and now this happens on restart when logging in:

unexpected fault address 0x7fb960f94000
fatal error: fault
[signal SIGBUS: bus error code=0x2 addr=0x7fb960f94000 pc=0x87e46a]

goroutine 102 gp=0xc000569a40 m=3 mp=0xc000068e08 [running]:
runtime.throw({0x1e4fa22?, 0x7?})
        /home/davec/sdk/go1.23.4/src/runtime/panic.go:1067 +0x48 fp=0xc0000465b0 sp=0xc000046580 pc=0x477d88
runtime.sigpanic()
        /home/davec/sdk/go1.23.4/src/runtime/signal_unix.go:914 +0x10a fp=0xc000046610 sp=0xc0000465b0 pc=0x479f0a
go.etcd.io/bbolt.(*page).fastCheck(0x7fb960f94000, 0x173f)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/page.go:57 +0x2a fp=0xc0000466d8 sp=0xc000046610 pc=0x87e46a
go.etcd.io/bbolt.(*Tx).page(0xc00826bdd0?, 0x1?)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/tx.go:534 +0x7b fp=0xc000046710 sp=0xc0000466d8 pc=0x880e5b
go.etcd.io/bbolt.(*Bucket).pageNode(0x20?, 0xc000046ac0?)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/bucket.go:748 +0x85 fp=0xc000046758 sp=0xc000046710 pc=0x871105
go.etcd.io/bbolt.(*Cursor).goToFirstElementOnTheStack(0xc000046860)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/cursor.go:181 +0xc7 fp=0xc0000467b8 sp=0xc000046758 pc=0x872587
go.etcd.io/bbolt.(*Cursor).next(0xc000046860)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/cursor.go:234 +0x52 fp=0xc0000467d8 sp=0xc0000467b8 pc=0x872892
go.etcd.io/bbolt.(*Cursor).Next(0x7fb978a4e79c?)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/cursor.go:94 +0x27 fp=0xc000046830 sp=0xc0000467d8 pc=0x872127
go.etcd.io/bbolt.(*Bucket).ForEach(0xc000046900?, 0xc000046908)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/bucket.go:396 +0x79 fp=0xc000046890 sp=0xc000046830 pc=0x86f979
decred.org/dcrdex/client/db/bolt.(*BoltDB).filteredMatches.func1(0xc000e7cb40?, 0xc0170a8100?)
        /home/davec/decred/dcrdex/client/db/bolt/db.go:1569 +0x15e fp=0xc000046948 sp=0xc000046890 pc=0x890e3e
decred.org/dcrdex/client/db/bolt.(*BoltDB).filteredMatches.(*BoltDB).matchesView.func2(0xc01072cc40)
        /home/davec/decred/dcrdex/client/db/bolt/db.go:1649 +0x84 fp=0xc0000469a0 sp=0xc000046948 pc=0x890c04
go.etcd.io/bbolt.(*DB).View(0x475f7f?, 0xc000046a58)
        /home/davec/go/pkg/mod/go.etcd.io/bbolt@v1.3.9/db.go:917 +0x6c fp=0xc000046a08 sp=0xc0000469a0 pc=0x8764ec
decred.org/dcrdex/client/db/bolt.(*BoltDB).matchesView(...)
        /home/davec/decred/dcrdex/client/db/bolt/db.go:1640
decred.org/dcrdex/client/db/bolt.(*BoltDB).filteredMatches(0x2a0000002a?, 0x2925fb0?, 0xf8?, 0x3?)
        /home/davec/decred/dcrdex/client/db/bolt/db.go:1563 +0x7a fp=0xc000046a78 sp=0xc000046a08 pc=0x890b1a
decred.org/dcrdex/client/db/bolt.(*BoltDB).MatchesForOrder(0x0?, {0xf, 0x2e, 0x8d, 0x61, 0xe1, 0x9c, 0x89, 0x30, 0x86, ...}, ...)
        /home/davec/decred/dcrdex/client/db/bolt/db.go:1550 +0x50 fp=0xc000046ac0 sp=0xc000046a78 pc=0x8909f0
decred.org/dcrdex/client/core.(*Core).dbTrackers(0xc000516c00, 0xc0000c3a00)
        /home/davec/decred/dcrdex/client/core/core.go:7366 +0x794 fp=0xc000046ee0 sp=0xc000046ac0 pc=0xa402d4
decred.org/dcrdex/client/core.(*Core).loadDBTrades(0xc000516c00, 0xc0000c3a00)
        /home/davec/decred/dcrdex/client/core/core.go:7456 +0x32 fp=0xc000047040 sp=0xc000046ee0 pc=0xa40d92
decred.org/dcrdex/client/core.(*Core).resolveActiveTrades(0xc000516c00, {0x2917740, 0xc000682050})
        /home/davec/decred/dcrdex/client/core/core.go:5241 +0x6d fp=0xc0000470b8 sp=0xc000047040 pc=0xa2d24d
decred.org/dcrdex/client/core.(*Core).Login(0xc000516c00, {0xc000bfe644, 0xa, 0xa})
        /home/davec/decred/dcrdex/client/core/core.go:4624 +0x3e5 fp=0xc000047280 sp=0xc0000470b8 pc=0xa27e05
decred.org/dcrdex/client/webserver.(*WebServer).actuallyLogin(0xc00037c1e0, {0x7fb99f9743f8, 0xc000bce740}, 0xc000344780, 0xc000bdc018?)
        /home/davec/decred/dcrdex/client/webserver/api.go:1511 +0x17d fp=0xc0000474d0 sp=0xc000047280 pc=0xbbfafd
decred.org/dcrdex/client/webserver.(*WebServer).apiLogin(0xc00037c1e0, {0x7fb99f9743f8, 0xc000bce740}, 0xc000344780)
        /home/davec/decred/dcrdex/client/webserver/api.go:1001 +0x106 fp=0xc000047588 sp=0xc0000474d0 pc=0xbbcbe6
decred.org/dcrdex/client/webserver.(*WebServer).apiLogin-fm({0x7fb99f9743f8?, 0xc000bce740?}, 0xc00066b5b8?)
        <autogenerated>:1 +0x36 fp=0xc0000475b8 sp=0xc000047588 pc=0xbd5876
...

[davecgh]

It seems pretty likely from looking at the code that it's trying to range over a nil bucket with .ForEach over a nil bucket.

[davecgh]

I was able to work around this by temporarily modifying the code to avoid the issue and it seems fine now, but there is clearly a bug that cause it to get into the state to begin with.