Bug 2236639

Summary:	EROFS doesn't zero mmap post-EOF tails on some files
Product:	[Fedora] Fedora	Reporter:	Alexander Maltsev <keltar.gw>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	37	CC:	acaringi, adscvr, airlied, alciregi, bskeggs, hdegoede, hpa, hsiangkao, jarod, josef, kernel-maint, lgoncalv, linville, masami256, mchehab, ptalbert, steved
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-6.4.14-200.fc38	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-09-07 01:29:10 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Alexander Maltsev 2023-09-01 04:18:08 UTC

There is a problem in kernel EROFS file system driver that causes wrong behaviour of mmap() on some files. It causes a crash in clang if system header files are stored in EROFS. Other software could be affected as mmap() is used extensively.

It is reproducible vith e.g. paching entire root file systemt o EROFS image with `lz4hc` compression option (the problem is not in compression itself; different compression option will trigger it on different files), mounting this image to subdirectory, and running `clang-cpp mountpoint/usr/include/stdlib.h`; clang-cpp produces some garbage output and crashes.

There are no EROFS-related messages in dmesg.

It affects any kernel up to (and including) 6.5. It should be fixed in 6.6 with this commit: https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git/commit/?id=e4c1cf523d820730a86cae2c6d55924833b6f7ac

It could be fixed in older kernels with this patch: https://lore.kernel.org/linux-erofs/20230831112959.99884-5-hsiangkao@linux.alibaba.com/T/

Could this fix be included in fc37 and rawhide please?

Reproducible: Always

Comment 1 Fedora Update System 2023-09-02 23:20:48 UTC

FEDORA-2023-eadae36e49 has been submitted as an update to Fedora 37. https://bodhi.fedoraproject.org/updates/FEDORA-2023-eadae36e49

Comment 2 Fedora Update System 2023-09-02 23:20:49 UTC

FEDORA-2023-f1812ce4c3 has been submitted as an update to Fedora 38. https://bodhi.fedoraproject.org/updates/FEDORA-2023-f1812ce4c3

Comment 3 Fedora Update System 2023-09-03 01:33:21 UTC

FEDORA-2023-eadae36e49 has been pushed to the Fedora 37 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2023-eadae36e49`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2023-eadae36e49

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 4 Fedora Update System 2023-09-03 02:23:00 UTC

FEDORA-2023-f1812ce4c3 has been pushed to the Fedora 38 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2023-f1812ce4c3`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2023-f1812ce4c3

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Gao Xiang 2023-09-04 05:20:20 UTC

yes, but it only impacts compressed files and will be fixed in all stable/LTS kernels.

Comment 6 Fedora Update System 2023-09-07 01:29:10 UTC

FEDORA-2023-f1812ce4c3 has been pushed to the Fedora 38 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 7 Fedora Update System 2023-09-08 01:33:14 UTC

FEDORA-2023-4d7e9e1dc5 has been pushed to the Fedora 37 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2023-4d7e9e1dc5`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2023-4d7e9e1dc5

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 8 Fedora Update System 2023-09-13 01:35:28 UTC

FEDORA-2023-4d7e9e1dc5 has been pushed to the Fedora 37 stable repository.
If problem still persists, please make note of it in this bug report.