Messages in this thread Patch in this message | | | Date | Sun, 7 May 2006 20:34:32 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] fs: fcntl_setlease defies lease_init assumptions |
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On Sun, 7 May 2006, Linus Torvalds wrote: > > Trond wrote an alternate patch for the actual problem which I sent > separately, but it would probably be good to have more safety in the slab > layer by default regardless.
And here's Trond's suggested locks.c fix.
Linus
--- From: Trond Myklebust <Trond.Myklebust@netapp.com> Subject: fs/locks.c: Fix lease_init Date: Sun, 07 May 2006 23:02:42 -0400
It is insane to be giving lease_init() the task of freeing the lock it is supposed to initialise, given that the lock is not guaranteed to be allocated on the stack. This causes lockups in fcntl_setlease(). Problem diagnosed by Daniel Hokka Zakrisson <daniel@hozac.com>
Also fix a slab leak in __setlease() due to an uninitialised return value. Problem diagnosed by Björn Steinbrink.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> ---
fs/locks.c | 21 ++++++++++++--------- 1 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/fs/locks.c b/fs/locks.c index abd9448..64b96b1 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -446,15 +446,14 @@ static struct lock_manager_operations le */ static int lease_init(struct file *filp, int type, struct file_lock *fl) { + if (assign_type(fl, type) != 0) + return -EINVAL; + fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_LEASE; - if (assign_type(fl, type) != 0) { - locks_free_lock(fl); - return -EINVAL; - } fl->fl_start = 0; fl->fl_end = OFFSET_MAX; fl->fl_ops = NULL; @@ -466,16 +465,19 @@ static int lease_init(struct file *filp, static int lease_alloc(struct file *filp, int type, struct file_lock **flp) { struct file_lock *fl = locks_alloc_lock(); - int error; + int error = -ENOMEM; if (fl == NULL) - return -ENOMEM; + goto out; error = lease_init(filp, type, fl); - if (error) - return error; + if (error) { + locks_free_lock(fl); + fl = NULL; + } +out: *flp = fl; - return 0; + return error; } /* Check if two locks overlap each other. @@ -1391,6 +1393,7 @@ static int __setlease(struct file *filp, goto out; if (my_before != NULL) { + *flp = *my_before; error = lease->fl_lmops->fl_change(my_before, arg); goto out; }
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