| Summary: | Ptrace requests may be masked by failed signal delivery. | ||
|---|---|---|---|
| Product: | frysk | Reporter: | Chris Moller <cmoller> |
| Component: | general | Assignee: | Andrew Cagney <cagney> |
| Status: | RESOLVED WORKSFORME | ||
| Severity: | normal | ||
| Priority: | P2 | ||
| Version: | unspecified | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
| Bug Depends on: | |||
| Bug Blocks: | 1496, 2654 | ||
| Attachments: | Testcase demonstrating the failure. | ||
Created attachment 1316 [details]
Testcase demonstrating the failure.
This t/c does two ptrace(PTRACE_DETACH...) operations. The first tries to
deliver an invalid signal--999--thereby failing (rc == -1) and inhibiting the
intended detach. The second delivers a valid SIGKILL and succeeds (rc == 0).
vanilla kernel's ptrace_detach also fails for invalid signal what is the errno in the real failure case? This is really "NOTABUG" but there's no option under "Resolve bug" for that. |
In ptrace requests that can also deliver a signal to the affected process, the request itself can be ignored if the signal delivery fails. E.g., in kerne/ptrace.c, the code for PTRACE_DETACH is: ret = ptrace_induce_signal(child, engine, data); if (!ret) ret = ptrace_detach(child, engine); Similar code exists in other places such as that for PTRACE_CONT. This code is in linux-2.6.17 with the utrace patches applied. The behaviour can be exercised by, e.g., calling ptrace(PTRACE_DETACH, pid, NULL, sig) where sig either is an invalid signal, or some internal conditions in ptrace.c aren't met. Also https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=206475