Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Created attachment 854158[details]
A patch file.
Description of problem:
strace -cf causes Segmentation fault before printing summary.
Version-Release number of selected component (if applicable):
strace-4.5.19-1.17.el6
How reproducible:
100%
Steps to Reproduce:
1. Install strace package and openjdk package.
2. Run "strace -cf java".
Actual results:
Segmentation fault
Expected results:
Summary is printed correctly.
Additional info:
The outf == NULL is the trigger when call_summary() in cleanup() is called.
static void
cleanup()
{
(...snipped...)
if (cflag)
call_summary(outf);
}
The outf == NULL is caused by assignments in handle_stopped_tcbs()
with tcp->outf == NULL and tcp->wait_status == 256 and tcp->pid == 0.
static int
handle_stopped_tcbs(struct tcb *tcp)
{
for (; tcp; tcp = tcp->next_need_service) {
int pid;
int status;
outf = tcp->outf;
status = tcp->wait_status;
pid = tcp->pid;
(...snipped...)
}
The tcp->outf == NULL is caused by assignments in droptcb() with
tcp->outf == stderr.
void
droptcb(tcp)
struct tcb *tcp;
{
if (tcp->pid == 0)
return;
(...snipped...)
if (outfname && followfork > 1 && tcp->outf)
fclose(tcp->outf);
tcp->outf = 0;
}
Oh, why are we closing stderr when we will later use stderr at call_summary()?
Attached patch solves "strace -cf java" case, but does not solve
"strace -cf -o outfile java" case. I don't know how to fix this bug.
Regards.
I'm not an expert in this code, but it looks like droptcb can drop both the incoming tcp argument, but also its parent via this call from within droptcb:
#ifdef LINUX
/* Update `tcp->parent->parent->nchildren' and the other fields
like NCLONE_DETACHED, only for zombie group leader that has
already reported and been short-circuited at the top of this
function. The same condition as at the top of DETACH. */
if ((tcp->flags & TCB_CLONE_THREAD) &&
tcp->parent->nclone_threads == 0 &&
(tcp->parent->flags & TCB_EXITING))
droptcb(tcp->parent);
#endif
We then continue the main loop in handle_stopped_tcbs which walks down a list of tcbs. If the parent appears later in that list, it will have already been dropped by the call to droptcb shown above. This ultimately results in the problems with tcp->outf that you're seeing.
My immediate recommendation as a workaround would be to use strace from the developer toolset. It does not exhibit this problem.
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://rhn.redhat.com/errata/RHBA-2015-1308.html
Created attachment 854158 [details] A patch file. Description of problem: strace -cf causes Segmentation fault before printing summary. Version-Release number of selected component (if applicable): strace-4.5.19-1.17.el6 How reproducible: 100% Steps to Reproduce: 1. Install strace package and openjdk package. 2. Run "strace -cf java". Actual results: Segmentation fault Expected results: Summary is printed correctly. Additional info: The outf == NULL is the trigger when call_summary() in cleanup() is called. static void cleanup() { (...snipped...) if (cflag) call_summary(outf); } The outf == NULL is caused by assignments in handle_stopped_tcbs() with tcp->outf == NULL and tcp->wait_status == 256 and tcp->pid == 0. static int handle_stopped_tcbs(struct tcb *tcp) { for (; tcp; tcp = tcp->next_need_service) { int pid; int status; outf = tcp->outf; status = tcp->wait_status; pid = tcp->pid; (...snipped...) } The tcp->outf == NULL is caused by assignments in droptcb() with tcp->outf == stderr. void droptcb(tcp) struct tcb *tcp; { if (tcp->pid == 0) return; (...snipped...) if (outfname && followfork > 1 && tcp->outf) fclose(tcp->outf); tcp->outf = 0; } Oh, why are we closing stderr when we will later use stderr at call_summary()? Attached patch solves "strace -cf java" case, but does not solve "strace -cf -o outfile java" case. I don't know how to fix this bug. Regards.