From: Xose Vazquez Perez <xose.vazquez@gmail.com>
To: Martin Wilck <mwilck@suse.com>,
Benjamin Marzinski <bmarzins@redhat.com>,
Christophe Varoqui <christophe.varoqui@opensvc.com>
Cc: DM_DEVEL-ML <dm-devel@lists.linux.dev>
Subject: [BUG] multipath-tools: 0 cyl reported on large disks due to overflow
Date: Fri, 22 May 2026 23:10:36 +0200 [thread overview]
Message-ID: <02a2bb69-c13d-43bb-bbed-2a1bd3007ba4@gmail.com> (raw)
Hi,
An integer overflow occurs in libmultipath/discovery.c:get_geometry() when
querying geometry on large disks resulting in "0 cyl" being reported:
# multipath -ll -d -v3
... | sdgm: 0 cyl, 64 heads, 32 sectors/track, start at 0
# fdisk -l /dev/sdgm
Disk /dev/sdgm: 12 TiB, 13194139533312 bytes, 25769803776 sectors
Units: sectors of 1 * 512 = 512 bytes
# dmesg | grep sdgm
sd 5:0:3:100: [sdgm] 25769803776 512-byte logical blocks: (13.2 TB/12.0TiB)
The root cause is that struct hd_geometry, from libmultipath/structs.h,
defines cylinders as an unsigned short.
Since it is a legacy interface, it should either sanitize the log output
or avoid relying on CHS geometry for large devices.
next reply other threads:[~2026-05-22 21:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-22 21:10 Xose Vazquez Perez [this message]
2026-05-26 19:28 ` [BUG] multipath-tools: 0 cyl reported on large disks due to overflow Benjamin Marzinski
2026-06-05 14:17 ` Martin Wilck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=02a2bb69-c13d-43bb-bbed-2a1bd3007ba4@gmail.com \
--to=xose.vazquez@gmail.com \
--cc=bmarzins@redhat.com \
--cc=christophe.varoqui@opensvc.com \
--cc=dm-devel@lists.linux.dev \
--cc=mwilck@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox