74 lines
2.2 KiB
Diff
74 lines
2.2 KiB
Diff
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
|
|
|