{"record":{"id":"435b2f301963a1bd","repo":"go-delve/delve","slug":"could-not-read-auxiliary-vector-v","errorCode":null,"errorMessage":"could not read auxiliary vector: %v","messagePattern":"could not read auxiliary vector: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/proc/native/proc_linux.go","lineNumber":939,"sourceCode":"\t\treturn nil\n\t}\n\t// For some reason the process will sometimes enter stopped state after a\n\t// detach, this doesn't happen immediately either.\n\t// We have to wait a bit here, then check if the main thread is stopped and\n\t// SIGCONT it if it is.\n\ttime.Sleep(50 * time.Millisecond)\n\tif s := status(dbp.pid, dbp.os.comm); s == 'T' {\n\t\t_ = sys.Kill(dbp.pid, sys.SIGCONT)\n\t}\n\treturn nil\n}\n\n// EntryPoint will return the process entry point address, useful for\n// debugging PIEs.\nfunc (dbp *nativeProcess) EntryPoint() (uint64, error) {\n\tauxvbuf, err := os.ReadFile(fmt.Sprintf(\"/proc/%d/auxv\", dbp.pid))\n\tif err != nil {\n\t\treturn 0, fmt.Errorf(\"could not read auxiliary vector: %v\", err)\n\t}\n\n\treturn linutil.EntryPointFromAuxv(auxvbuf, dbp.bi.Arch.PtrSize()), nil\n}\n\nfunc (dbp *nativeProcess) SetUProbe(fnName string, goidOffset int64, args []ebpf.UProbeArgMap) error {\n\t// Lazily load and initialize the BPF program upon request to set a uprobe.\n\tif dbp.os.ebpf == nil {\n\t\tvar err error\n\t\tdbp.os.ebpf, err = ebpf.LoadEBPFTracingProgram(dbp.bi.Images[0].Path)\n\t\tif err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\t// We only allow up to 12 args for a BPF probe.\n\t// 6 inputs + 6 outputs.\n\t// Return early if we have more.","sourceCodeStart":921,"sourceCodeEnd":957,"githubUrl":"https://github.com/go-delve/delve/blob/a23773e6c31361e43246bc43a424ee009679b174/pkg/proc/native/proc_linux.go#L921-L957","documentation":"nativeProcess.EntryPoint reads /proc/<pid>/auxv via os.ReadFile to locate the dynamic loader's entry point, which is required to debug PIE (position-independent) executables. If the auxv file cannot be read (e.g. the process has exited and /proc/<pid> is gone, or permission is denied), the error is wrapped and returned. Without auxv, Delve cannot compute the entry point and cannot properly initialize the debug session for PIE binaries.","triggerScenarios":"Calling EntryPoint (internally during launch/attach initialization of a PIE binary) when /proc/<pid>/auxv cannot be opened: process already terminated, insufficient permissions, or the pid no longer exists.","commonSituations":"Attaching to a process that exits during startup; running dlv inside a container without CAP_SYS_PTRACE targeting a different user's process; hidepid mount option on /proc restricting visibility of other users' processes; kernel hardening (ptrace_scope=2/3).","solutions":["Ensure the target process is still alive when attaching (use ps -p <pid> immediately before dlv attach).","Fix permissions: run dlv as the same user as the target or with sufficient capabilities (CAP_SYS_PTRACE in containers).","Lower /proc/sys/kernel/yama/ptrace_scope (e.g. echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope) if it blocks access.","If using containers, launch with docker run --cap-add=SYS_PTRACE --security-opt seccomp=unconfined."],"exampleFix":"// before: attach races with process exit\ncmd.Start()\ndlv.Attach(pid) // process may already be gone\n// after: wait for readiness before attaching\ncmd.Start()\nfor !portReady(\"127.0.0.1:4040\") { time.Sleep(50 * time.Millisecond) }\ndlv.Attach(pid)","handlingStrategy":"validation","validationCode":"// verify auxv readability before starting a PIE debug session\nif _, err := os.ReadFile(fmt.Sprintf(\"/proc/%d/auxv\", pid)); err != nil {\n    return fmt.Errorf(\"cannot access auxv for pid %d: %w\", pid, err)\n}\n// also verify process is alive\nif _, err := os.Stat(fmt.Sprintf(\"/proc/%d\", pid)); err != nil {\n    return fmt.Errorf(\"process %d not running\", pid)\n}","typeGuard":null,"tryCatchPattern":"_, err := debugger.Attach(pid)\nif err != nil && strings.Contains(err.Error(), \"could not read auxiliary vector\") {\n    // check whether the process died or permissions are insufficient\n    if _, statErr := os.Stat(fmt.Sprintf(\"/proc/%d/auxv\", pid)); statErr != nil {\n        // process gone: restart it and re-attach\n    } else {\n        // permission problem: elevate capabilities or fix ptrace_scope\n    }\n}","preventionTips":["Confirm the target process is alive before dlv attach","Run dlv as the same user as the target, or add CAP_SYS_PTRACE in containers","Avoid hidepid /proc mounts or run as root when they are required","Set kernel.yama.ptrace_scope appropriately on hardened systems"],"tags":["linux","procfs","permissions","pie"],"backgroundTag":"proc-entry-not-found","analyzedSha":"a23773e6c31361e43246bc43a424ee009679b174","analyzedAt":"2026-08-31T15:12:45.221Z","schemaVersion":2},"datasetVersion":"2026-08-31T19:17:28.585Z"}