Correct locking and cancellation cleanup in syslog functions (RHEL-78390)

Resolves: RHEL-78390

glibc-RHEL-78390.patch

@@ -0,0 +1,114 @@
+commit c4e4b2e149705559d28b16a9b47ba2f6142d6a6c
+Author: Andreas Schwab <schwab@suse.de>
+Date:   Tue Jun 23 12:55:49 2020 +0200
+
+    Correct locking and cancellation cleanup in syslog functions (bug 26100)
+    
+    Properly serialize the access to the global state shared between the
+    syslog functions, to avoid races in multithreaded processes.  Protect a
+    local allocation in the __vsyslog_internal function from leaking during
+    cancellation.
+
+diff --git a/misc/syslog.c b/misc/syslog.c
+index fd6537edf6..2cc63ef287 100644
+--- a/misc/syslog.c
++++ b/misc/syslog.c
+@@ -91,14 +91,20 @@ struct cleanup_arg
+ static void
+ cancel_handler (void *ptr)
+ {
+-#ifndef NO_SIGPIPE
+   /* Restore the old signal handler.  */
+   struct cleanup_arg *clarg = (struct cleanup_arg *) ptr;
+ 
+-  if (clarg != NULL && clarg->oldaction != NULL)
+-    __sigaction (SIGPIPE, clarg->oldaction, NULL);
++  if (clarg != NULL)
++    {
++#ifndef NO_SIGPIPE
++      if (clarg->oldaction != NULL)
++	__sigaction (SIGPIPE, clarg->oldaction, NULL);
+ #endif
+ 
++      /* Free the memstream buffer,  */
++      free (clarg->buf);
++    }
++
+   /* Free the lock.  */
+   __libc_lock_unlock (syslog_lock);
+ }
+@@ -169,9 +175,17 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
+ 		pri &= LOG_PRIMASK|LOG_FACMASK;
+ 	}
+ 
++	/* Prepare for multiple users.  We have to take care: most
++	   syscalls we are using are cancellation points.  */
++	struct cleanup_arg clarg;
++	clarg.buf = NULL;
++	clarg.oldaction = NULL;
++	__libc_cleanup_push (cancel_handler, &clarg);
++	__libc_lock_lock (syslog_lock);
++
+ 	/* Check priority against setlogmask values. */
+ 	if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
+-		return;
++		goto out;
+ 
+ 	/* Set default facility if none specified. */
+ 	if ((pri & LOG_FACMASK) == 0)
+@@ -235,6 +249,9 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
+ 	    /* Close the memory stream; this will finalize the data
+ 	       into a malloc'd buffer in BUF.  */
+ 	    fclose (f);
++
++	    /* Tell the cancellation handler to free this buffer.  */
++	    clarg.buf = buf;
+ 	  }
+ 
+ 	/* Output to stderr if requested. */
+@@ -252,22 +269,10 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
+ 		    v->iov_len = 1;
+ 		  }
+ 
+-		__libc_cleanup_push (free, buf == failbuf ? NULL : buf);
+-
+ 		/* writev is a cancellation point.  */
+ 		(void)__writev(STDERR_FILENO, iov, v - iov + 1);
+-
+-		__libc_cleanup_pop (0);
+ 	}
+ 
+-	/* Prepare for multiple users.  We have to take care: open and
+-	   write are cancellation points.  */
+-	struct cleanup_arg clarg;
+-	clarg.buf = buf;
+-	clarg.oldaction = NULL;
+-	__libc_cleanup_push (cancel_handler, &clarg);
+-	__libc_lock_lock (syslog_lock);
+-
+ #ifndef NO_SIGPIPE
+ 	/* Prepare for a broken connection.  */
+  	memset (&action, 0, sizeof (action));
+@@ -320,6 +325,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
+ 		__sigaction (SIGPIPE, &oldaction, (struct sigaction *) NULL);
+ #endif
+ 
++ out:
+ 	/* End of critical section.  */
+ 	__libc_cleanup_pop (0);
+ 	__libc_lock_unlock (syslog_lock);
+@@ -430,8 +436,14 @@ setlogmask (int pmask)
+ {
+ 	int omask;
+ 
++	/* Protect against multiple users.  */
++	__libc_lock_lock (syslog_lock);
++
+ 	omask = LogMask;
+ 	if (pmask != 0)
+ 		LogMask = pmask;
++
++	__libc_lock_unlock (syslog_lock);
++
+ 	return (omask);
+ }

glibc.spec

@@ -115,7 +115,7 @@ end \
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: %{glibcrelease}.13
+Release: %{glibcrelease}.14
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -1258,6 +1258,7 @@ Patch1023: glibc-RHEL-8381-7.patch
 Patch1024: glibc-RHEL-8381-8.patch
 Patch1025: glibc-RHEL-8381-9.patch
 Patch1026: glibc-RHEL-8381-10.patch
+Patch1027: glibc-RHEL-78390.patch
 
 ##############################################################################
 # Continued list of core "glibc" package information:
@@ -2919,6 +2920,9 @@ fi
 %{_libdir}/libpthread_nonshared.a
 
 %changelog
+* Tue Feb 11 2025 Patsy Griffin <patsy@redhat.com> - 2.28-251.14
+- Correct locking and cancellation cleanup in syslog functions (RHEL-78390)
+
 * Fri Feb  7 2025 Carlos O'Donell <carlos@redhat.com> - 2.28-251.13
 - Restore internal ABI to avoid tooling false positives (RHEL-8381)