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Description of problem: When pldd is running against an application, if the the SIGSTOP signal is not delivered to the tracee immediately after PTRACE_ATTACH, pldd will not wait for the tracee to stop before continuing.

Version-Release number of selected component (if applicable):
glibc-common 2.17-222

How reproducible:
Issue is randomly reproducible as a result of the race between the delivery of SIGSTOP and PTRACE_DETACH. Incidence of this issue increases if done in a virtual machine.

Steps to Reproduce:
1. Run "pldd $$" to trace the bash shell.

Actual results:
At random, bash will remain in T state after pldd's trace has completed until a SIGCONT is delivered.

Expected results:
After pldd is finished, bash is resumed.

Additional info:
The Sourceware bug also includes a patch.

Andrew,

Thanks for the bug report and the pointers to the patch that solves the problem.

We will review this as part of our normal bug review process.

If you have an questions or if this issue starts to impact any customers, please raise the severity.

Verified,
reproduced in glibc-2.17-260.el7 on x86_64 and s390x,
didn't reproduce in glibc-2.17-270.el7

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2019:2118