| Summary: | sys-kernel/genkernel-next-70 and/or dev-util/ccache-3.7.7-r1 and/or sys-kernel/gentoo-sources-5.5.8 is replacing /dev/null with a file | ||
|---|---|---|---|
| Product: | Gentoo Linux | Reporter: | Dan Goodliffe <gentoo> |
| Component: | Current packages | Assignee: | Ettore Di Giacinto (RETIRED) <mudler> |
| Status: | RESOLVED OBSOLETE | ||
| Severity: | major | CC: | genkernel, jstein, kernel |
| Priority: | Normal | ||
| Version: | unspecified | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Package list: | Runtime testing required: | --- | |
| Attachments: |
genkernel configuration
"ccache -p" as root Kernel .config strace when run as root strace when run as user |
||
Created attachment 617946 [details]
genkernel configuration
Created attachment 617948 [details]
"ccache -p" as root
Created attachment 617950 [details]
Kernel .config
No, it's this... just haven't figured out yet what process that is.
151070 rename("/dev/null", "/dev/null.rm.akira.151070.XXXXXX") = 0
151070 unlink("/dev/null.rm.akira.151070.XXXXXX") = 0
Ah, basically the same.
151070 execve("/usr/lib/ccache/bin/cc", ["/usr/lib/ccache/bin/cc", "-Werror", "-Wmaybe-uninitialized", "-S", "-x", "c", "/dev/null", "-o", "/dev/null"], 0x561819dbd000 /* 142 vars */) = 0
Runing as user command
$ strace -y -f /usr/lib/ccache/bin/cc -Werror -Wmaybe-uninitialized -S -x c /dev/null -o /dev/null |& fgrep dev/null |& fgrep -i unli
I don't see an attempt to delete /dev/null.
Do you observe that command to delete a file for you? If it does please attach full strace output.
Created attachment 619256 [details]
strace when run as root
See line 450, rename of /dev/null.
Created attachment 619258 [details]
strace when run as user
It's different by paths and addresses, but vimdiff can match enough to make sense. The rename at 450 is never attempted.
Yeah, it's a ccache's deficiency. genkernel-next should not run builds as root either though. I guess genkernel itself is also able to trigger that because we don't use sandbox when building kernel. Looks like it's specific to 'hard_link = true' option. Filed https://github.com/ccache/ccache/issues/564 for ccache upstream. But even if it gets fixed I would expect more problems like that if you run builds as root. The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=650d7b15773aea3eda20f2b870ad3266ddeefa6d commit 650d7b15773aea3eda20f2b870ad3266ddeefa6d Author: Sergei Trofimovich <slyfox@gentoo.org> AuthorDate: 2020-03-24 22:27:06 +0000 Commit: Sergei Trofimovich <slyfox@gentoo.org> CommitDate: 2020-03-24 22:29:55 +0000 dev-util/ccache: backport workaround for /dev/null clobber In bug #712080 'hard_link = true' mode of ccache unlinked /dev/null as ccache was running as root. This workaround allows /dev/null to survive. Other special files still stay affected. Bug: https://bugs.gentoo.org/712080 Package-Manager: Portage-2.3.95, Repoman-2.3.21 Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> dev-util/ccache/ccache-3.7.8-r1.ebuild | 71 +++++++++++++++++++++++ dev-util/ccache/files/ccache-3.7.8-dev-null.patch | 57 ++++++++++++++++++ 2 files changed, 128 insertions(+) Removing toolchain@ from CC. Fell free to readd for further ccache-related questions. Package removed. |
Yeah I know, I thought I was mad too. Running genkernel (at least with my config) invokes ccache (as its "cc") and that replaces /dev/null with a file. Using the steps below, I think I've found half of the problem: 151075 execve("/usr/lib/ccache/bin/cc", ["/usr/lib/ccache/bin/cc", "-Werror", "-D__SIZEOF_INT128__=0", "-S", "-x", "c", "/dev/null", "-o", "/dev/null"], 0x55c8400f6000 /* 142 vars */) = 0 That's the last mention of "/dev/null" before the first occurrence of stat returning it as a file, not a char device. I'm just not sure which bits of the packages mentioned are actually at fault. I've set it to major as replacement of /dev/null with these permissions practically cripples everything for users until fixed. Reproducible: Always Steps to Reproduce: 1. ls -l /dev/null crw-rw-rw- 1 root root 1, 3 Mar 10 19:36 /dev/null 2. strace -fo /var/tmp/str genkernel --kernel-outputdir=/var/tmp/kernel/build all * Gentoo Linux Genkernel; Version 70 * Running with options: --kernel-outputdir=/var/tmp/kernel/build all * Using genkernel.conf from /etc/genkernel.conf * Sourcing arch-specific config.sh from /usr/share/genkernel/arch/x86_64/config.sh .. * Sourcing arch-specific modules_load from /usr/share/genkernel/arch/x86_64/modules_load .. * Linux Kernel 5.5.8-gentoo for x86_64... * .. with config file /usr/share/genkernel/arch/x86_64/kernel-config * kernel: --mrproper is disabled; not running 'make mrproper'. * >> Running oldconfig... (this doesn't need to run to completion) 3. ls -l /dev/null -rw-r--r-- 1 root root 0 Mar 10 19:37 /dev/null I'll attach configuration files shortly. Portage 2.3.93 (python 3.6.10-final-0, default/linux/amd64/17.0/desktop/plasma/systemd, gcc-9.2.0, glibc-2.30-r4, 5.5.5-gentoo x86_64) ================================================================= System uname: Linux-5.5.5-gentoo-x86_64-Intel-R-_Core-TM-_i7-3820_CPU_@_3.60GHz-with-gentoo-2.7 KiB Mem: 8134516 total, 1371820 free KiB Swap: 8388604 total, 8388604 free Timestamp of repository gentoo: Tue, 10 Mar 2020 18:57:01 +0000 Head commit of repository gentoo: faeb40151010875e46c45ec83d37eb9577ae24c8 sh bash 5.0_p16 ld GNU ld (Gentoo 2.34 p1) 2.34.0 distcc 3.3.3 x86_64-pc-linux-gnu [disabled] ccache version 3.7.7 [disabled] app-shells/bash: 5.0_p16::gentoo dev-java/java-config: 2.2.0-r4::gentoo dev-lang/perl: 5.30.1::gentoo dev-lang/python: 2.7.17-r1::gentoo, 3.6.10::gentoo, 3.7.6::gentoo, 3.8.2::gentoo dev-util/ccache: 3.7.7-r1::gentoo dev-util/cmake: 3.16.5::gentoo dev-util/pkgconfig: 0.29.2::gentoo sys-apps/baselayout: 2.7::gentoo sys-apps/sandbox: 2.18::gentoo 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