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Martin Milata:
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RFE: dwfl_core_file_report: use NT_FILE core note if the link_map chain is broken
https://bugzilla.redhat.com/show_bug.cgi?id=1129777
The dwfl_core_file_report function follows dynamic linker's link_map chain in
order to determine the shared libraries used by the executable. As this data
structure is located in writable memory it can be overwritten by garbage, which
is sometimes the case.
https://github.com/abrt/satyr/issues/127#issuecomment-46957546
Since version 3.7 (commit 2aa362c49), Linux kernel adds NT_FILE note to core
files which contains the files mapped by the process, including shared
libraries.
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dwfl_core_file_report now tries to fall back on NT_FILE if the link_map chain
is broken.
elfutils would already find the appropriate binary file from
/usr/lib/debug/.build-id/ symbolic links. But those symbolic links do not have
to be present on the system while NT_FILE still points to the correct binaries.
Filenames from the note NT_FILE are used only if link_map filenames failed to
locate matching binaries.
tests/test-core.core.bz2 had to have its NT_FILE disabled as run-unstrip-n.sh
otherwise FAILs:
FAIL: 0x7f67f2aaf000+0x202000 - . - /home/jkratoch/redhat/elfutils-libregr/test-core-lib.so
PASS: 0x7f67f2aaf000+0x202000 - . - test-core-lib.so
As test-core-lib.so is found in link_map but it is not present on the disk
elfutils now chooses the more reliable filename from NT_FILE (although that
filename is also not found on the disk). Updating the expected text would be
also sufficient.
libdwfl/
2014-09-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Support NT_FILE for locating files.
* core-file.c (dwfl_core_file_report): New variables note_file and
note_file_size, set them and pass them to dwfl_segment_report_module.
* dwfl_segment_report_module.c: Include common.h and fcntl.h.
(buf_has_data, buf_read_ulong, handle_file_note): New functions.
(invalid_elf): New function from code of dwfl_segment_report_module.
(dwfl_segment_report_module): Add parameters note_file and
note_file_size. New variables elf and fd, clean them up in finish.
Move some code to invalid_elf. Call handle_file_note, if it found
a name verify the file by invalid_elf. Protect elf and fd against
cleanup by finish if we found the file for new Dwfl_Module.
* libdwflP.h (dwfl_segment_report_module): Add parameters note_file and
note_file_size.
tests/
2014-09-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Support NT_FILE for locating files.
* Makefile.am (TESTS): Add run-linkmap-cut.sh.
(EXTRA_DIST): Add run-linkmap-cut.sh, linkmap-cut-lib.so.bz2,
linkmap-cut.bz2 and linkmap-cut.core.bz2 .
* linkmap-cut-lib.so.bz2: New file.
* linkmap-cut.bz2: New file.
* linkmap-cut.core.bz2: New file.
* run-linkmap-cut.sh: New file.
* run-unstrip-n.sh: Update its expected output.
Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>
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