115 lines
3.2 KiB
Diff
115 lines
3.2 KiB
Diff
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);
|
|
}
|