Bug 1335297 - SHT_X86_64_UNWIND section type not recognized by elflint, readelf, possibly other
Summary: SHT_X86_64_UNWIND section type not recognized by elflint, readelf, possibly o...
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: elfutils
Version: 25
Hardware: x86_64
OS: All
unspecified
unspecified
Target Milestone: ---
Assignee: Mark Wielaard
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-05-11 19:52 UTC by David L Kreitzer
Modified: 2017-12-12 10:45 UTC (History)
7 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2017-12-12 10:45:54 UTC
Type: Bug
Embargoed:


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System ID Private Priority Status Summary Last Updated
Sourceware 20079 0 None None None 2016-05-12 15:07:26 UTC

Description David L Kreitzer 2016-05-11 19:52:34 UTC
Recent versions of clang use the ABI-suggested SHT_X86_64_UNWIND section type for the stack unwinding information in .eh_frame. elfutils does not handle this well. readelf shows the section type as "SHT_LOPROC+1", and elflint reports an error.


bash-4.2$ cat t.c
void f2();
void f1() { f2(); }
bash-4.2$ clang -c t.c
bash-4.2$ readelf --version
readelf (elfutils) 0.166
Copyright (C) 2012 Red Hat, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Ulrich Drepper.
bash-4.2$ readelf -S t.o
There are 9 section headers, starting at offset 0x1a8:

Section Headers:
[Nr] Name                 Type         Addr             Off      Size     ES Flags Lk Inf Al
[ 0]                      NULL         0000000000000000 00000000 00000000  0        0   0  0
[ 1] .strtab              STRTAB       0000000000000000 00000158 0000004e  0        0   0  1
[ 2] .text                PROGBITS     0000000000000000 00000040 0000000d  0 AX     0   0 16
[ 3] .rela.text           RELA         0000000000000000 00000128 00000018 24        8   2  8
[ 4] .comment             PROGBITS     0000000000000000 0000004d 00000028  1 MS     0   0  1
[ 5] .note.GNU-stack      PROGBITS     0000000000000000 00000075 00000000  0        0   0  1
[ 6] .eh_frame            SHT_LOPROC+1 0000000000000000 00000078 00000038  0 A      0   0  8
[ 7] .rela.eh_frame       RELA         0000000000000000 00000140 00000018 24        8   6  8
[ 8] .symtab              SYMTAB       0000000000000000 000000b0 00000078 24        1   3  8

bash-4.2$ elflint t.o
section [ 3] '.rela.text': relocation 0: invalid type
section [ 6] '.eh_frame' has unsupported type 1879048193
section [ 7] '.rela.eh_frame': invalid destination section type
section [ 7] '.rela.eh_frame': relocation 0: invalid type

Comment 1 Mark Wielaard 2016-05-11 20:52:33 UTC
Do you have a pointer to the spec that defines this?
Is this just for .eh_frame (which is currently just SHT_PROGBITS)?
Or also .eh_frame_hdr?

The first step would be to add submit this new constant to the glibc project elf.h header. Other projects take elf.h from glibc and use those definitions.

Comment 2 Mark Wielaard 2016-05-11 20:58:23 UTC
Note to the reporter that this bug is both marked as "private", but also filed against Fedora. That means it is not really private. It is public to the reporter, some internal Red Hat groups and all fedora hackers subscribed to elfutils bugs (see the CC list).

Comment 3 David L Kreitzer 2016-05-12 15:03:07 UTC
The x86_64 ABI documents SHT_X86_64_UNWIND in 4.2.2 - 4.2.4: http://www.x86-64.org/documentation/abi.pdf.

I'm not sure about .eh_frame_hdr. The ABI doesn't mention it. As far as I can tell, ld always uses SHT_PROGBITS, but that is not very conclusive. I'll raise the issue on the ABI mailing list.

I submitted this request to get SHT_X86_64_UNWIND added to elf.h:
https://sourceware.org/bugzilla/show_bug.cgi?id=20079

Sorry about the public vs. private confusion. My intent in checking multiple boxes was to make the report visible to anyone.

Comment 4 Mark Wielaard 2016-05-12 15:13:41 UTC
(In reply to David L Kreitzer from comment #3)
> The x86_64 ABI documents SHT_X86_64_UNWIND in 4.2.2 - 4.2.4:
> http://www.x86-64.org/documentation/abi.pdf.
> 
> I'm not sure about .eh_frame_hdr. The ABI doesn't mention it. As far as I
> can tell, ld always uses SHT_PROGBITS, but that is not very conclusive. I'll
> raise the issue on the ABI mailing list.

Thanks.

> I submitted this request to get SHT_X86_64_UNWIND added to elf.h:
> https://sourceware.org/bugzilla/show_bug.cgi?id=20079

I added myself to the CC of that bug.

> Sorry about the public vs. private confusion. My intent in checking multiple
> boxes was to make the report visible to anyone.

Aha, checking any box makes the bug private to those groups.
If you want it to become a public bug, then no group box needs to be checked.

Comment 5 Jan Kurik 2016-07-26 04:39:31 UTC
This bug appears to have been reported against 'rawhide' during the Fedora 25 development cycle.
Changing version to '25'.

Comment 6 Fedora End Of Life 2017-11-16 18:49:56 UTC
This message is a reminder that Fedora 25 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
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Comment 7 Fedora End Of Life 2017-12-12 10:45:54 UTC
Fedora 25 changed to end-of-life (EOL) status on 2017-12-12. Fedora 25 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

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