x/tools/gopls: impossible crash in strings.HasPrefix

[adonovan]

#!stacks
"sigpanic" && "strings.HasPrefix"

Issue created by stacks.

More memory corruption.

This stack 4017FQ was reported by telemetry:

• crash/crash
• runtime.throw:+9,+0x33
• runtime.sigpanic:+16,+0x163
• internal/stringslite.HasPrefix:=17,+0x28
• strings.HasPrefix:=521,+0x48
• golang.org/x/tools/gopls/internal/protocol.filename:+8,+0x4c
• golang.org/x/tools/gopls/internal/protocol.DocumentURI.Path:+1,+0x1f
• golang.org/x/tools/gopls/internal/protocol.DocumentURI.DirPath:+1,+0x1f
• golang.org/x/tools/gopls/internal/cache.invalidatedPackageIDs:+39,+0x24f
• golang.org/x/tools/gopls/internal/cache.(*Snapshot).clone:+195,+0xfbf
• golang.org/x/tools/gopls/internal/cache.(*Session).invalidateViewLocked:+25,+0x19b
• golang.org/x/tools/gopls/internal/cache.(*Session).DidModifyFiles:+158,+0xdc3
• golang.org/x/tools/gopls/internal/server.(*server).didModifyFiles:+36,+0x2ef
• golang.org/x/tools/gopls/internal/server.(*server).DidClose:+4,+0x147
• golang.org/x/tools/gopls/internal/protocol.serverDispatch:+245,+0x1537
• golang.org/x/tools/gopls/internal/lsprpc.(*StreamServer).ServeStream.ServerHandler.func4:+5,+0x6f
• golang.org/x/tools/gopls/internal/lsprpc.(*StreamServer).ServeStream.handshaker.func5:+52,+0x637
• golang.org/x/tools/gopls/internal/protocol.Handlers.MustReplyHandler.func1:+2,+0xb3
• golang.org/x/tools/gopls/internal/protocol.Handlers.AsyncHandler.func2.2:+3,+0x7f

golang.org/x/tools/gopls@v0.20.0 go1.25.4 darwin/arm64 gopls.client=vscode (1)

Use this command to reproduce the executable:
(HOME=$(mktemp -d); GOOS=darwin GOARCH=arm64 GOTOOLCHAIN=go1.25.4 go install golang.org/x/tools/gopls@v0.20.0 && find $HOME/go/bin -type f)
To disassemble: go tool objdump exe | less

[gabyhelp]

Related Issues

• x/tools/gopls: SEGV in string comparison in mapaccess #76159
• x/tools/gopls: SEGV in HasSuffix (corrupt string) #74348
• x/tools/gopls: SEGV accessing g in function prolog (R28 is nil or invalid) #76158
• x/tools/gopls: impossible crash in (*types.Checker).basicLit #76329
• x/tools/gopls: sigpanic in methods of persistent.Map (corrupt g) #74870
• x/tools/gopls: DidChangeWatchedFiles: impossible crash in growslice #75465
• x/tools/gopls: crash in append (invalid string data pointer) #73586
• x/tools/gopls: corrupt g in printf.run #75232
• x/tools/gopls: impossible panic in BlockStmt.End (type checking IfStmt with nil Body) #76327
• x/tools/gopls: impossible panic reading rtype.hash in type assertion #76328

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