Bug 2343526 - tcpdump crashes with -w -Z root options
Summary: tcpdump crashes with -w -Z root options
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: tcpdump
Version: 42
Hardware: All
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Michal Ruprich
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-02-03 14:19 UTC by Miroslav Lichvar
Modified: 2026-02-22 00:58 UTC (History)
3 users (show)

Fixed In Version: tcpdump-4.99.6-2.fc43 tcpdump-4.99.6-2.fc42
Clone Of:
Environment:
Last Closed: 2026-02-17 00:56:11 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description Miroslav Lichvar 2025-02-03 14:19:52 UTC
When tcpdump is configured by -Z root to not drop root privileges (as documented in the man page) and write to a pcap file, it segfaults on start.

This seems to be an interaction of the downstream patch delaying the dropping of root privileges and the following upstream change included in tcpdump-4.99.5 setting the username variable to NULL:

https://github.com/the-tcpdump-group/tcpdump/commit/75866fb1db0b52ce70940e113e48fa353fb00d1e


Reproducible: Always

Comment 1 Miroslav Lichvar 2025-02-03 14:21:51 UTC
Here is a PR to fix the downstream patch:
https://src.fedoraproject.org/rpms/tcpdump/pull-request/9

Comment 2 Aoife Moloney 2025-02-26 13:50:01 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 42 development cycle.
Changing version to 42.

Comment 3 Fedora Update System 2026-02-13 17:15:38 UTC
FEDORA-2026-0bd5fbaa7d (tcpdump-4.99.6-2.fc42) has been submitted as an update to Fedora 42.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-0bd5fbaa7d

Comment 4 Fedora Update System 2026-02-13 17:15:38 UTC
FEDORA-2026-62cb5273ef (tcpdump-4.99.6-2.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-62cb5273ef

Comment 5 Fedora Update System 2026-02-14 00:53:49 UTC
FEDORA-2026-0bd5fbaa7d has been pushed to the Fedora 42 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-0bd5fbaa7d`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-0bd5fbaa7d

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

Comment 6 Fedora Update System 2026-02-14 01:30:15 UTC
FEDORA-2026-62cb5273ef has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-62cb5273ef`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-62cb5273ef

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

Comment 7 Fedora Update System 2026-02-17 00:56:11 UTC
FEDORA-2026-62cb5273ef (tcpdump-4.99.6-2.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 8 Fedora Update System 2026-02-22 00:58:34 UTC
FEDORA-2026-0bd5fbaa7d (tcpdump-4.99.6-2.fc42) has been pushed to the Fedora 42 stable repository.
If problem still persists, please make note of it in this bug report.


Note You need to log in before you can comment on or make changes to this bug.