Turn OFD locks back on with glibc workaround

Resolves: #1274922
This commit is contained in:
Robbie Harwood 2016-08-15 17:32:27 +00:00
parent 766ee8e989
commit 136cc25087
2 changed files with 80 additions and 3 deletions

View File

@ -0,0 +1,73 @@
From 65110210b75d38908cdd84cb202cf013ccf6ed0e Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Sun, 14 Aug 2016 12:08:16 -0400
Subject: [PATCH] Work around glibc OFD lock bug on 32-bit Linux
A bug in Gnu libc causes OFD locking to fail unpredictably on 32-bit
Linux, typically leading to deadlocks. Work around this bug by using
the fcntl64 system call and struct flock64.
See also: https://sourceware.org/bugzilla/show_bug.cgi?id=20251
ticket: 8474
target_version: 1.14-next
tags: pullup
---
src/lib/krb5/os/lock_file.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/src/lib/krb5/os/lock_file.c b/src/lib/krb5/os/lock_file.c
index a2f247c..2360c96 100644
--- a/src/lib/krb5/os/lock_file.c
+++ b/src/lib/krb5/os/lock_file.c
@@ -43,7 +43,29 @@
#if defined(HAVE_FCNTL_H) && defined(F_SETLKW) && defined(F_RDLCK)
#define POSIX_FILE_LOCKS
+
+/*
+ * Gnu libc bug 20251, currently unfixed, breaks OFD lock support on
+ * 32-bit platforms. Work around this bug by explicitly using the
+ * fcntl64 system call and struct flock64.
+ */
+#if defined(__linux__) && __WORDSIZE == 32
+#include <sys/syscall.h>
+#ifdef SYS_fcntl64
+#define USE_FCNTL64
#endif
+#endif
+#ifdef USE_FCNTL64
+/* Use the fcntl64 system call and struct flock64. (Gnu libc does not
+ * define a fcntl64() function, so we must use syscall().) */
+#define fcntl(fd, cmd, arg) syscall(SYS_fcntl64, fd, cmd, arg)
+typedef struct flock64 fcntl_lock_st;
+#else
+/* Use regular fcntl() and struct flock. */
+typedef struct flock fcntl_lock_st;
+#endif
+
+#endif /* defined(HAVE_FCNTL_H) && defined(F_SETLKW) && defined(F_RDLCK) */
#ifdef HAVE_FLOCK
#ifndef sysvimp
@@ -66,7 +88,7 @@
* older kernel than we were built with.
*/
static int
-ofdlock(int fd, int cmd, struct flock *lock_arg)
+ofdlock(int fd, int cmd, fcntl_lock_st *lock_arg)
{
#ifdef F_OFD_SETLKW
int st, ofdcmd;
@@ -89,7 +111,7 @@ krb5_lock_file(krb5_context context, int fd, int mode)
krb5_error_code retval = 0;
#ifdef POSIX_FILE_LOCKS
int lock_cmd = F_SETLKW;
- struct flock lock_arg = { 0 };
+ fcntl_lock_st lock_arg = { 0 };
#endif
switch (mode & ~KRB5_LOCKMODE_DONTBLOCK) {
--
2.8.1

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@ -13,7 +13,7 @@
Summary: The Kerberos network authentication system
Name: krb5
Version: 1.14.3
Release: 4%{?dist}
Release: 5%{?dist}
# - Maybe we should explode from the now-available-to-everybody tarball instead?
# http://web.mit.edu/kerberos/dist/krb5/1.13/krb5-1.13.2-signed.tar
# - The sources below are stored in a lookaside cache. Upload with
@ -56,7 +56,7 @@ Patch71: krb5-1.13-dirsrv-accountlock.patch
Patch86: krb5-1.9-debuginfo.patch
Patch129: krb5-1.11-run_user_0.patch
Patch134: krb5-1.11-kpasswdtest.patch
Patch148: krb5-disable_ofd_locks.patch
Patch148: krb5-1.14.4-ofd-lock-workaround.patch
Patch150: krb5-acquire_cred_interposer.patch
Patch153: krb5-1.14.1-log_file_permissions.patch
@ -264,7 +264,7 @@ ln NOTICE LICENSE
%patch134 -p1 -b .kpasswdtest
%patch148 -p1 -b .disable_ofd_locks
%patch148 -p1 -b .ofd-lock-workaround
%patch150 -p1 -b .fix_interposer
%patch153 -p1 -b .log_file_permissions
@ -742,6 +742,10 @@ exit 0
%{_libdir}/libkadm5srv_mit.so.*
%changelog
* Mon Aug 15 2016 Robbie Harwood <rharwood@redhat.com> - 1.14.3-5
- Turn OFD locks back on with glibc workaround
- Resolves: #1274922
* Wed Aug 10 2016 Robbie Harwood <rharwood@redhat.com> - 1.14.3-4
- Fix use of KKDCPP with SNI
- Resolves: #1365027