---------- Forwarded message ---------- Date: Mon, 15 Aug 2016 11:37:12 -0400 From: Greg Hudson <ghud...@mit.edu> Reply-To: krb...@mit.edu To: cvs-k...@mit.edu Subject: krb5 commit: Work around glibc OFD lock bug on 32-bit Linux
https://github.com/krb5/krb5/commit/65110210b75d38908cdd84cb202cf013ccf6ed0e commit 65110210b75d38908cdd84cb202cf013ccf6ed0e Author: Greg Hudson <ghud...@mit.edu> Date: Sun Aug 14 12:08:16 2016 -0400 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 files 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) { _______________________________________________ cvs-krb5 mailing list cvs-k...@mit.edu https://mailman.mit.edu/mailman/listinfo/cvs-krb5
