Bug 119136 - CAN-2004-2259 vsftpd is very secure but not very stable
CAN-2004-2259 vsftpd is very secure but not very stable
Status: CLOSED ERRATA
Product: Fedora
Classification: Fedora
Component: vsftpd (Show other bugs)
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All Linux
medium Severity medium
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Assigned To: Bill Nottingham
Mike McLean
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Depends On:
Blocks:
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Reported: 2004-03-25 08:57 EST by Olivier Baudron
Modified: 2014-03-16 22:43 EDT (History)
1 user (show)

See Also:
Fixed In Version: 1.2.1-4
Doc Type: Bug Fix
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Last Closed: 2004-04-28 23:03:36 EDT
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RHEL 7.3 requirements from Atomic Host:


Attachments (Terms of Use)
Fix block/unblock signal bug (1.54 KB, text/plain)
2004-03-25 08:59 EST, Olivier Baudron
no flags Details

  None (edit)
Description Olivier Baudron 2004-03-25 08:57:22 EST
There is a signal handle problem in vsftpd-1.2.1-2.

The SIGCHLD handle is a complexe function with malloc()s and free()s
inside. Neither malloc() nor free() is re-entrant, so the SIGCHLD
signal must be caught only at safe locations.

This is not the case:

// Pseudo-code
standalone.c:
    unblock_signal(SIGCHLD)
    socket = my_accept(...)
    block_signal(SIGCHLD)

sysutil.c:
    my_accept(...) {
        malloc(...)   // BUG: may be interrupted!
        free(...)     // BUG: may be interrupted!
        accept(...)
    }
// End

The unblock/block mecanism must be used more strictly around the
blocking systems calls. A patch follows. Hopefully, it will fix
bug 109933.
Comment 1 Olivier Baudron 2004-03-25 08:59:47 EST
Created attachment 98850 [details]
Fix block/unblock signal bug
Comment 2 Olivier Baudron 2004-04-28 04:46:53 EDT
I reported the problem to the author and the issue has been fixed in
the new upstream release 1.2.2. The patch is a bit different of mine.
Some structures have been rewritten so that malloc() and free() are
not used  in the "accept" routine.
Comment 3 Bill Nottingham 2004-04-28 23:03:36 EDT
This is patched in 1.2.1-4.
Comment 4 John Flanagan 2004-05-11 23:20:40 EDT
An errata has been issued which should help the problem described in this bug report. 
This report is therefore being closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files, please follow the link below. You may reopen 
this bug report if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2004-164.html

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