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70 lines
3.4 KiB
70 lines
3.4 KiB
1 year ago
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From 7924438d595c7c77ead2e9ed475212fab7792fe4 Mon Sep 17 00:00:00 2001
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1 year ago
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From: Romain Geissler <romain.geissler@amadeus.com>
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Date: Tue, 20 Jun 2023 16:06:31 +0000
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Subject: [PATCH] elf-util: discard PT_LOAD segment early based on the start
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address.
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Indeed when iterating over all the PT_LOAD segment of the core dump
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while trying to look for the elf headers of a given module, we iterate
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over them all and try to use the first one for which we can parse a
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package metadata, but the start address is never taken into account,
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so absolutely nothing guarantees we actually parse the right ELF header
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of the right module we are currently iterating on.
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This was tested like this:
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- Create a core dump using sleep on a fedora 37 container, with an
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explicit LD_PRELOAD of a library having a valid package metadata:
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podman run -t -i --rm -v $(pwd):$(pwd) -w $(pwd) fedora:37 bash -x -c \
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'LD_PRELOAD=libreadline.so.8 sleep 1000 & SLEEP_PID="$!" && sleep 1 && kill -11 "${SLEEP_PID}" && mv "core.${SLEEP_PID}" the-core'
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- Then from a fedora 38 container with systemd installed, the resulting
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core dump has been passed to systemd-coredump with and without this
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patch. Without this patch, we get:
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Module /usr/bin/sleep from rpm bash-5.2.15-3.fc38.x86_64
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Module /usr/lib64/libtinfo.so.6.3 from rpm coreutils-9.1-8.fc37.x86_64
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Module /usr/lib64/libc.so.6 from rpm coreutils-9.1-8.fc37.x86_64
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Module /usr/lib64/libreadline.so.8.2 from rpm coreutils-9.1-8.fc37.x86_64
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Module /usr/lib64/ld-linux-x86-64.so.2 from rpm coreutils-9.1-8.fc37.x86_64
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While with this patch we get:
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Module /usr/bin/sleep from rpm bash-5.2.15-3.fc38.x86_64
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Module /usr/lib64/libtinfo.so.6.3 from rpm ncurses-6.3-5.20220501.fc37.x86_64
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Module /usr/lib64/libreadline.so.8.2 from rpm readline-8.2-2.fc37.x86_64
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So the parsed package metadata reported by systemd-coredump when the module
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files are not found on the host (ie the case of crash inside a container) are
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now correct. The inconsistency of the first module in the above example
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(sleep is indeed not provided by the bash package) can be ignored as it
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is a consequence of how this was tested.
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In addition to this, this also fixes the performance issue of
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systemd-coredump in case of the crashing process uses a large number of
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shared libraries and having no package metadata, as reported in
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https://sourceware.org/pipermail/elfutils-devel/2023q2/006225.html.
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(cherry picked from commit 21a2c735e2bfdc3bfdc42f894d6e3d00f4a38dcd)
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1 year ago
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Resolves: #2215412
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1 year ago
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---
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src/shared/elf-util.c | 4 ++++
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1 file changed, 4 insertions(+)
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diff --git a/src/shared/elf-util.c b/src/shared/elf-util.c
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index 181735409d..d746f3ab3f 100644
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--- a/src/shared/elf-util.c
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+++ b/src/shared/elf-util.c
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@@ -538,6 +538,10 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name,
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if (!program_header || program_header->p_type != PT_LOAD)
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continue;
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+ /* This PT_LOAD segment doesn't contain the start address, so it can't be the module we are looking for. */
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+ if (start < program_header->p_vaddr || start >= program_header->p_vaddr + program_header->p_memsz)
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+ continue;
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+
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/* Now get a usable Elf reference, and parse the notes from it. */
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data = sym_elf_getdata_rawchunk(elf,
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program_header->p_offset,
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