[Bug libc/17144] New: syslog is not thread-safe if NO_SIGPIPE is not defined

[Bug libc/17144] New: syslog is not thread-safe if NO_SIGPIPE is not defined

[bugdal at aerifal dot cx]

https://sourceware.org/bugzilla/show_bug.cgi?id=17144

            Bug ID: 17144
           Summary: syslog is not thread-safe if NO_SIGPIPE is not defined
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: bugdal at aerifal dot cx
                CC: drepper.fsp at gmail dot com

The Linux wrapper for misc/syslog.c defines NO_SIGPIPE and defines send_flags
to MSG_NOSIGNAL so that SIGPIPE suppression is not needed. However if this file
is ever used for non-Linux systems, the SIGPIPE suppression it does via
sigaction is non-conforming to the POSIX requirement that syslog be
thread-safe.

MSG_NOSIGNAL was added to POSIX in the 2008 edition, so I think the
Linux-specific syslog.c should just be removed and instead the generic file
should either assume MSG_NOSIGNAL is available, or check for it directly with
#ifdef and have a thread-safe fallback if it's not defined. The thread-safe
fallback is easy:

1. Block SIGPIPE with the signal mask.
2. Perform the operation that might raise SIGPIPE.
3. Clear any pending SIGPIPE with sigtimedwait and a zero timeout.
4. Unblock SIGPIPE.

However I doubt it's needed. The offending code should probably just be
removed.

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[Bug libc/17144] syslog is not thread-safe if NO_SIGPIPE is not defined

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17144

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com
              Flags|                            |security-

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[Bug libc/17144] syslog is not thread-safe if NO_SIGPIPE is not defined

[adhemerval.zanella at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=17144

Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |adhemerval.zanella at linaro dot o
                   |                            |rg
   Target Milestone|---                         |2.34
                 CC|                            |adhemerval.zanella at linaro dot o
                   |                            |rg
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
Fixed on 2.34.

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