From: Matthew Wilcox <willy@debian.org>
This patch fixes a memory leak in the file locking code. Each attempt to
unlock a file would result in the leak of a file lock. Many thanks to
Martin Josefsson for providing the testcase which enabled me to figure out
the problem.
25-akpm/fs/locks.c | 21 ++++++++++++++-------
1 files changed, 14 insertions(+), 7 deletions(-)
diff -puN fs/locks.c~file-locking-leak-fix fs/locks.c
--- 25/fs/locks.c~file-locking-leak-fix Fri Sep 12 14:05:05 2003
+++ 25-akpm/fs/locks.c Fri Sep 12 14:05:05 2003
@@ -221,7 +221,7 @@ void locks_copy_lock(struct file_lock *n
static inline int flock_translate_cmd(int cmd) {
if (cmd & LOCK_MAND)
return cmd & (LOCK_MAND | LOCK_RW);
- switch (cmd &~ LOCK_NB) {
+ switch (cmd) {
case LOCK_SH:
return F_RDLCK;
case LOCK_EX:
@@ -233,8 +233,8 @@ static inline int flock_translate_cmd(in
}
/* Fill in a file_lock structure with an appropriate FLOCK lock. */
-static int flock_make_lock(struct file *filp,
- struct file_lock **lock, unsigned int cmd)
+static int flock_make_lock(struct file *filp, struct file_lock **lock,
+ unsigned int cmd)
{
struct file_lock *fl;
int type = flock_translate_cmd(cmd);
@@ -247,7 +247,7 @@ static int flock_make_lock(struct file *
fl->fl_file = filp;
fl->fl_pid = current->tgid;
- fl->fl_flags = (cmd & LOCK_NB) ? FL_FLOCK : FL_FLOCK | FL_SLEEP;
+ fl->fl_flags = FL_FLOCK;
fl->fl_type = type;
fl->fl_end = OFFSET_MAX;
@@ -1298,6 +1298,7 @@ asmlinkage long sys_flock(unsigned int f
{
struct file *filp;
struct file_lock *lock;
+ int can_sleep, unlock;
int error;
error = -EBADF;
@@ -1305,12 +1306,18 @@ asmlinkage long sys_flock(unsigned int f
if (!filp)
goto out;
- if ((cmd != LOCK_UN) && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
+ can_sleep = !(cmd & LOCK_NB);
+ cmd &= ~LOCK_NB;
+ unlock = (cmd == LOCK_UN);
+
+ if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3))
goto out_putf;
error = flock_make_lock(filp, &lock, cmd);
if (error)
goto out_putf;
+ if (can_sleep)
+ lock->fl_flags |= FL_SLEEP;
error = security_file_lock(filp, cmd);
if (error)
@@ -1318,7 +1325,7 @@ asmlinkage long sys_flock(unsigned int f
for (;;) {
error = flock_lock_file(filp, lock);
- if ((error != -EAGAIN) || (cmd & LOCK_NB))
+ if ((error != -EAGAIN) || !can_sleep)
break;
error = wait_event_interruptible(lock->fl_wait, !lock->fl_next);
if (!error)
@@ -1329,7 +1336,7 @@ asmlinkage long sys_flock(unsigned int f
}
out_free:
- if (error) {
+ if (unlock || error) {
locks_free_lock(lock);
}
_