Bug#1121758: dpkg-deb crashing on liblzma5
Control: tag -1 moreinfo unreproducible Hi! On Mon, 2025-12-01 at 23:33:10 +0100, Eduard Bloch wrote: > Package: liblzma5 > Version: 5.8.1-2 > Severity: serious > see below for the stacktrace. This nonsense started a few days ago. The > system is perfectly stable otherwise, so I don't think this is a > hardware issue. > > So I was trying to compile an upstream Linux kernel. Command, which has > been working for years, is: > > $ nice -n20 make bindeb-pkg -j14 KCFLAGS='-march=x86-64-v3 -mtune=znver3' > > And now it keeps segfaulting, like: > > STRIP > debian/linux-image-6.18.0/lib/modules/6.18.0/kernel/virt/lib/irqbypass.ko > DEPMOD debian/linux-image-6.18.0/lib/modules/6.18.0 > dpkg-deb: Paket »linux-image-6.18.0« wird in > »../linux-image-6.18.0_6.18.0-84_amd64.deb« gebaut. > dh_builddeb: error: dpkg-deb --root-owner-group --build > debian/linux-image-6.18.0 .. died with signal 13 > dh_builddeb: error: Aborting due to earlier error > make[3]: *** [debian/rules:66: binary-image] Fehler 2 > > And why? The stacktrace from coredumpctl reveals: > > #0 0x7f4343d7b058 in bt_skip_func (len_limit=64, pos=8388609, > cur=cur@entry=0x7f4308379010 "\200\005", cur_match=253073, depth=47, > son=0x7f42fefbd010, cyclic_pos=0, cyclic_size=8388609) > at ../../../../src/liblzma/lz/lz_encoder_mf.c:546 > warning: 546 ../../../../src/liblzma/lz/lz_encoder_mf.c: Datei oder > Verzeichnis nicht gefunden > [Current thread is 1 (Thread 0x7f4314e6f6c0 (LWP 3883979))] > (gdb) bt > #0 0x7f4343d7b058 in bt_skip_func (len_limit=64, pos=8388609, > cur=cur@entry=0x7f4308379010 "\200\005", cur_match=253073, depth=47, > son=0x7f42fefbd010, cyclic_pos=0, cyclic_size=8388609) > at ../../../../src/liblzma/lz/lz_encoder_mf.c:546 > #1 0x7f4343d7bebe in lzma_mf_bt4_skip (mf=0x7f4304000c88, amount=1) at > ../../../../src/liblzma/lz/lz_encoder_mf.c:740 > #2 0x7f4343d7cdef in mf_skip (mf=0x7f4304000c88, amount=1) at > ../../../../src/liblzma/lz/lz_encoder.h:294 > #3 encode_init (coder=0x7f433c4f9010, mf=0x7f4304000c88) at > ../../../../src/liblzma/lzma/lzma_encoder.c:282 > #4 lzma_lzma_encode (coder=0x7f433c4f9010, mf=mf@entry=0x7f4304000c88, > out=out@entry=0x7f4304000e06 "", out_pos=out_pos@entry=0x7f4304000df0, > out_size=out_size@entry=65536, limit=2096879) > at ../../../../src/liblzma/lzma/lzma_encoder.c:318 > #5 0x7f4343d845cd in lzma2_encode (coder_ptr=0x7f4304000d60, > mf=0x7f4304000c88, out=0x7f430a7fe050 "", out_pos=0x7f4314e6ee88, > out_size=25167072) at ../../../../src/liblzma/lzma/lzma2_encoder.c:188 > #6 0x7f4343d7a5c3 in lz_encode (coder_ptr=0x7f4304000c60, allocator=0x0, > in=0x7f4308ffd010 "\200\005", in_pos=0x7f4314e6ee90, in_size=16384, > out=0x7f430a7fe050 "", out_pos=0x7f4314e6ee88, out_size=25167072, > action=LZMA_RUN) > at ../../../../src/liblzma/lz/lz_encoder.c:176 > #7 0x7f4343d6e27c in block_encode (coder_ptr=0x7f4304000b70, > allocator=, in=0x7f4308ffd010 "\200\005", > in_pos=0x7f4314e6ee90, in_size=, out=0x7f430a7fe050 "", > out_pos=0x7f4314e6ee88, out_size=25167072, > action=LZMA_RUN) at ../../../../src/liblzma/common/block_encoder.c:63 > #8 0x7f4343d71907 in worker_encode (thr=0x55af3efeb580, > out_pos=0x7f4314e6ee88, state=) at > ../../../../src/liblzma/common/stream_encoder_mt.c:294 > #9 worker_start (thr_ptr=0x55af3efeb580) at > ../../../../src/liblzma/common/stream_encoder_mt.c:393 > #10 0x7f4343b12b7b in start_thread (arg=) at > ./nptl/pthread_create.c:448 > #11 0x7f4343b907b8 in __GI___clone3 () at > ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78 > > But why? > > Okay, then I wanted to install one of my existing kernel-image DEBs. And then > initramfs build also started crashing. > > But why? The common factor here was, again, liblzma5! > > So I have changed the compression type of initramfs to zstd and now it > works... somehow. Still not explaining what is happening with liblzma5 here. I cannot reproduce this problem within liblzma5 (which would seem independent from dpkg, that has seen no upload since the release of Debian stable). On Tue, 2025-12-02 at 21:28:43 +0100, Eduard Bloch wrote: > I checked the symptoms again. I can call the command shown in the > stacktrace with the same arguments and it does not crash. With or > without fakeroot. > > Then I tried injecting the same env. vars (extracted from the coredump) > into the shell prior to calling. Still no crash. > > Then I tried the run in gdb directly. Result: > > (gdb) run --root-owner-group --build debian/linux-image-6.18.0 .. > Starting program: /usr/bin/dpkg-deb --root-owner-group --build > debian/linux-image-6.18.0 .. > [Thread debugging using libthread_db enabled] > Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". > dpkg-deb: Paket »linux-image-6.18.0« wird in > »../linux-image-6.18.0_6.18.0-85_amd64.deb« gebaut. > [Detaching after fork from child process 1135101] > [Detaching after fork from child pro
Bug#1121758: dpkg-deb crashing on liblzma5
Package: liblzma5 Version: 5.8.1-2 Severity: serious Hi, see below for the stacktrace. This nonsense started a few days ago. The system is perfectly stable otherwise, so I don't think this is a hardware issue. So I was trying to compile an upstream Linux kernel. Command, which has been working for years, is: $ nice -n20 make bindeb-pkg -j14 KCFLAGS='-march=x86-64-v3 -mtune=znver3' And now it keeps segfaulting, like: STRIP debian/linux-image-6.18.0/lib/modules/6.18.0/kernel/virt/lib/irqbypass.ko DEPMOD debian/linux-image-6.18.0/lib/modules/6.18.0 dpkg-deb: Paket »linux-image-6.18.0« wird in »../linux-image-6.18.0_6.18.0-84_amd64.deb« gebaut. dh_builddeb: error: dpkg-deb --root-owner-group --build debian/linux-image-6.18.0 .. died with signal 13 dh_builddeb: error: Aborting due to earlier error make[3]: *** [debian/rules:66: binary-image] Fehler 2 And why? The stacktrace from coredumpctl reveals: #0 0x7f4343d7b058 in bt_skip_func (len_limit=64, pos=8388609, cur=cur@entry=0x7f4308379010 "\200\005", cur_match=253073, depth=47, son=0x7f42fefbd010, cyclic_pos=0, cyclic_size=8388609) at ../../../../src/liblzma/lz/lz_encoder_mf.c:546 warning: 546../../../../src/liblzma/lz/lz_encoder_mf.c: Datei oder Verzeichnis nicht gefunden [Current thread is 1 (Thread 0x7f4314e6f6c0 (LWP 3883979))] (gdb) bt #0 0x7f4343d7b058 in bt_skip_func (len_limit=64, pos=8388609, cur=cur@entry=0x7f4308379010 "\200\005", cur_match=253073, depth=47, son=0x7f42fefbd010, cyclic_pos=0, cyclic_size=8388609) at ../../../../src/liblzma/lz/lz_encoder_mf.c:546 #1 0x7f4343d7bebe in lzma_mf_bt4_skip (mf=0x7f4304000c88, amount=1) at ../../../../src/liblzma/lz/lz_encoder_mf.c:740 #2 0x7f4343d7cdef in mf_skip (mf=0x7f4304000c88, amount=1) at ../../../../src/liblzma/lz/lz_encoder.h:294 #3 encode_init (coder=0x7f433c4f9010, mf=0x7f4304000c88) at ../../../../src/liblzma/lzma/lzma_encoder.c:282 #4 lzma_lzma_encode (coder=0x7f433c4f9010, mf=mf@entry=0x7f4304000c88, out=out@entry=0x7f4304000e06 "", out_pos=out_pos@entry=0x7f4304000df0, out_size=out_size@entry=65536, limit=2096879) at ../../../../src/liblzma/lzma/lzma_encoder.c:318 #5 0x7f4343d845cd in lzma2_encode (coder_ptr=0x7f4304000d60, mf=0x7f4304000c88, out=0x7f430a7fe050 "", out_pos=0x7f4314e6ee88, out_size=25167072) at ../../../../src/liblzma/lzma/lzma2_encoder.c:188 #6 0x7f4343d7a5c3 in lz_encode (coder_ptr=0x7f4304000c60, allocator=0x0, in=0x7f4308ffd010 "\200\005", in_pos=0x7f4314e6ee90, in_size=16384, out=0x7f430a7fe050 "", out_pos=0x7f4314e6ee88, out_size=25167072, action=LZMA_RUN) at ../../../../src/liblzma/lz/lz_encoder.c:176 #7 0x7f4343d6e27c in block_encode (coder_ptr=0x7f4304000b70, allocator=, in=0x7f4308ffd010 "\200\005", in_pos=0x7f4314e6ee90, in_size=, out=0x7f430a7fe050 "", out_pos=0x7f4314e6ee88, out_size=25167072, action=LZMA_RUN) at ../../../../src/liblzma/common/block_encoder.c:63 #8 0x7f4343d71907 in worker_encode (thr=0x55af3efeb580, out_pos=0x7f4314e6ee88, state=) at ../../../../src/liblzma/common/stream_encoder_mt.c:294 #9 worker_start (thr_ptr=0x55af3efeb580) at ../../../../src/liblzma/common/stream_encoder_mt.c:393 #10 0x7f4343b12b7b in start_thread (arg=) at ./nptl/pthread_create.c:448 #11 0x7f4343b907b8 in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78 But why? Okay, then I wanted to install one of my existing kernel-image DEBs. And then initramfs build also started crashing. But why? The common factor here was, again, liblzma5! So I have changed the compression type of initramfs to zstd and now it works... somehow. Still not explaining what is happening with liblzma5 here. Best regards, Eduard. -- System Information: Debian Release: forky/sid APT prefers unstable-debug APT policy: (500, 'unstable-debug'), (500, 'oldoldstable'), (500, 'unstable'), (500, 'testing'), (1, 'experimental-debug'), (1, 'experimental') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 6.18.0-rc5+ (SMP w/16 CPU threads; PREEMPT) Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages dpkg depends on: ii libbz2-1.0 1.0.8-6 ii libc62.41-12 ii liblzma5 5.8.1-2 ii libmd0 1.1.0-2+b1 ii libselinux1 3.9-2 ii libzstd1 1.5.7+dfsg-2 ii tar 1.35+dfsg-3.1 ii zlib1g 1:1.3.dfsg+really1.3.1-1+b1 dpkg recommends no packages. Versions of packages dpkg suggests: ii apt3.1.12 pn debsig-verify -- no debconf information -- Atheismus ist keine Philosophie, er ist noch nicht ein mal eine Weltsicht. Er ist schlichtweg die Weigerung, ohne Grund das Gegenteil des Offensichtlichen zu glauben.
