Bug 1051221 - Untraced symbols cause SIGSEGV in some PPC64 binaries
Summary: Untraced symbols cause SIGSEGV in some PPC64 binaries
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: ltrace
Version: 7.0
Hardware: Unspecified
OS: Unspecified
Target Milestone: rc
: ---
Assignee: Petr Machata
QA Contact: Michael Petlan
Depends On:
TreeView+ depends on / blocked
Reported: 2014-01-09 21:21 UTC by Petr Machata
Modified: 2015-05-05 01:38 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2014-06-13 13:19:37 UTC
Target Upstream Version:

Attachments (Terms of Use)

Description Petr Machata 2014-01-09 21:21:22 UTC
Description of problem:
I see this on my PPC64 box:

$ ltrace -f -e __libc_start_main -- /bin/true 
[pid 19908] true->__libc_start_main(1, 0xfffd4369c88, 0xfffd4369c98, 0xfffd4369de0breakpoint_on_continue 0x10003cc0 __libc_start_main
 <no return ...>
[pid 19908] --- SIGSEGV (Segmentation fault) ---
[pid 19908] +++ killed by SIGSEGV +++

But when I request tracing of all symbols that are actually called:

$ ltrace -f -e __libc_start_main+exit -- /bin/true 
[pid 19935] true->__libc_start_main(1, 0xffff1c4adf8, 0xffff1c4ae08, 0xffff1c4af50b <unfinished ...>
[pid 19935] true->exit(0, 0xffff1c4adf8, 0xffff1c4ae08, 0xffff1c4af50 <no return ...>
[pid 19935] +++ exited (status 0) +++

I think the problem might be in the part of the PPC64 backend that does unprelinking, but couldn't reproduce this on handcrafted binaries.

Version-Release number of selected component (if applicable):

Comment 1 Petr Machata 2014-01-10 19:34:39 UTC
This is now fixed in upstream as well as in Fedora.  The problem was indeed in unprelinking.

Comment 2 Petr Machata 2014-01-10 19:43:03 UTC
The problem can be reproduced as follows:

$ cat w.c
int main (void) {
$ gcc w.c 
$ strip a.out 
$ prelink ./a.out 

# This works:
$ ./ltrace  ~/tmp/a.out 
__libc_start_main(1, 0xfffc73b1f78, 0xfffc73b1f88, 0xfffc73b20d0 <unfinished ...>
puts(0x10000740, 0xfffc73b1f78, 0xfffc73b1f88, 0xfffc73b20d0ble
)                                    = 4
+++ exited (status 48) +++

# This doesn't:
$ ltrace -e __libc_start_main ./a.out 
a.out->__libc_start_main(1, 0xfffdf3d3368, 0xfffdf3d3378, 0xfffdf3d34c0 <no return ...>
--- SIGSEGV (Segmentation fault) ---
+++ killed by SIGSEGV +++

Comment 4 Michael Petlan 2014-02-13 15:08:13 UTC
Tested with ltrace-0.7.91-4 (reproduced) and ltrace-0.7.91-[56] (works well).


Comment 5 Ludek Smid 2014-06-13 13:19:37 UTC
This request was resolved in Red Hat Enterprise Linux 7.0.

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