linux-ext4 - [Bug 18372] New: A filled up named pipe always has a size of zero!

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 12 Sep 2010 21:47:04 GMT
From:	bugzilla-daemon@...zilla.kernel.org
To:	linux-ext4@...r.kernel.org
Subject: [Bug 18372] New: A filled up named pipe always has a size of zero!

https://bugzilla.kernel.org/show_bug.cgi?id=18372

           Summary: A filled up named pipe always has a size of zero!
           Product: File System
           Version: 2.5
    Kernel Version: 2.6.32-22-generic (also older and newer ones)
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: ext4
        AssignedTo: fs_ext4@...nel-bugs.osdl.org
        ReportedBy: tom.bzliknl83947@...ine.de
                CC: tom.bzliknl83947@...ine.de
        Regression: No

Hi, there!

The size of a filled named pipe is always zero. This is wrong! A read operation
is going to hang for try to read from an empty pipe. To go around this trap it
is necessary to do a conditional test on the filesize, [ -s pipe ]. Problem:
The test doesn't work, because filesize is always zero.

Try:
mknod pipe &
sleep 3600  <>pipe &
echo 'date' >pipe
[ -s pipe ] && echo "filled up"
ls -l pipe; stat pipe    # if size zero, it is wrong
[ -s pipe ] && (read val <pipe; echo $val)

This is a critical error. While parallel processing a script would be blocked.
In worst case it causes a deadlock situation. Every changing of a condition of
a file should be reported whithin the i-node. 

I found it in several disto: Ubuntu KarmicKoala 9.1, LucidLynx 10.04,
Linux Mint Debian Edition 5, Slackware 13.1 x64

Best regards
TOM

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html