rpms/gdb
7
0
Fork 0
Code Issues Pull Requests Releases Activity

Backport "Save/restore file offset while reading notes in core file"

Browse Source 
(Keith Seitz, RHBZ 1931344)

Resolves: RHBZ 1931344
This commit is contained in:
Keith Seitz 2021-03-31 14:49:14 -07:00
parent 9a3fa11c4d
commit 0a3a5ea5a6
5 changed files with 99 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
_gdb.spec.Patch.include
View File

@ -424,3 +424,7 @@ Patch104: testing-custom-inputrc.patch
# (Tom de Vries)
Patch105: process_psymtab_comp_unit-type-unit.patch
# Backport "Save/restore file offset while reading notes in core file"
# (Keith Seitz, RHBZ 1931344)
Patch106: gdb-rhbz1931344-bfd_seek-elf_read_notes.patch

1
_gdb.spec.patch.include
View File

@ -103,3 +103,4 @@
%patch103 -p1
%patch104 -p1
%patch105 -p1
%patch106 -p1

1
_patch_order
View File

@ -103,3 +103,4 @@ gdb-rhbz1909902-frame_id_p-assert-2.patch
gdb-rhbz1941080-fix-gdbserver-hang.patch
testing-custom-inputrc.patch
process_psymtab_comp_unit-type-unit.patch
gdb-rhbz1931344-bfd_seek-elf_read_notes.patch

87
gdb-rhbz1931344-bfd_seek-elf_read_notes.patch Normal file
View File

@ -0,0 +1,87 @@
From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
From: Keith Seitz <keiths@redhat.com>
Date: Thu, 25 Mar 2021 10:31:48 -0700
Subject: gdb-rhbz1931344-bfd_seek-elf_read_notes.patch
;; Backport "Save/restore file offset while reading notes in core file"
;; (Keith Seitz, RHBZ 1931344)
A recent bug (RH BZ 1931344) has exposed a bug in the core file
build-ID support that I introduced a while ago. It is pretty
easy to demonstate the problem following a simplified procedure
outlined in that bug:
[shell1]
shell1$ /usr/libexec/qemu-kvm
[shell2]
shell2$ pkill -SEGV -x qemu-kvm
[shell1]
Segmentation fault (core dumped)
Load this core file into GDB without specifying an executable
(an unfortunate Fedora/RHEL-ism), and GDB will inform the user
to install debuginfo for the "missing" executable:
$ gdb -nx -q core.12345
...
Missing separate debuginfo for the main executable file
Try: dnf --enablerepo='*debug*' install /usr/lib/debug/.build-id/e2/e9c66d3117fb2bbb5b2be122f04f2664e5df54
Core was generated by `/usr/libexec/qemu-kvm'.
Program terminated with signal SIGSEGV, Segmentation fault.
...
The suggested build-ID is actaully for gmp not qemu-kvm. The problem
lies in _bfd_elf_core_find_build_id, where we loop over program headers
looking for note segments:
/* Read in program headers and parse notes. */
for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr)
{
Elf_External_Phdr x_phdr;
if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
goto fail;
elf_swap_phdr_in (abfd, &x_phdr, i_phdr);
if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
{
elf_read_notes (abfd, offset + i_phdr->p_offset,
i_phdr->p_filesz, i_phdr->p_align);
if (abfd->build_id != NULL)
return TRUE;
}
elf_read_notes uses bfd_seek to forward the stream to the location of
the note segment. When control returns to _bfd_elf_core_fild_build_id,
the stream is no longer in the location looking at program headers, and
all subsequent reads will read from the wrong file offset.
To fix this, this patch marks the stream location and ensures
that it is restored after elf_read_notes is called.
bfd/ChangeLog
2021-03-26 Keith Seitz <keiths@redhat.com>
* elfcore.h (_bfd_elf_core_find_build_id): Seek file
offset of program headers after calling elf_read_notes.
diff --git a/bfd/elfcore.h b/bfd/elfcore.h
--- a/bfd/elfcore.h
+++ b/bfd/elfcore.h
@@ -410,6 +410,13 @@ NAME(_bfd_elf, core_find_build_id)
{
elf_read_notes (abfd, offset + i_phdr->p_offset,
i_phdr->p_filesz, i_phdr->p_align);
+
+ /* Make sure ABFD returns to processing the program headers. */
+ if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff
+ + (i + 1) * sizeof (x_phdr)),
+ SEEK_SET) != 0)
+ goto fail;
+
if (abfd->build_id != NULL)
return TRUE;
}

8
gdb.spec
View File

@ -37,7 +37,7 @@ Version: 10.1
# The release always contains a leading reserved number, start it at 1.
# `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing.
Release: 17%{?dist}
Release: 18%{?dist}
License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and LGPLv3+ and BSD and Public Domain and GFDL
# Do not provide URL for snapshots as the file lasts there only for 2 days.
@ -1190,7 +1190,11 @@ fi
%endif
%changelog
* Wed Mar 31 2021 Jonathan Wakely <jwakely@redhat.com>
* Wed Mar 31 2021 Keith Seitz <keiths@redhat.com> - 10.1-18
- Backport "Save/restore file offset while reading notes in core file"
(Keith Seitz, RHBZ 1931344)
* Wed Mar 31 2021 Jonathan Wakely <jwakely@redhat.com> - 10.1-17
- Rebuilt for removed libstdc++ symbols (#1937698)
* Tue Mar 23 2021 Kevin Buettner <kevinb@redhat.com>