diff options
| author | David Teigland <teigland@redhat.com> | 2009-06-18 20:20:24 +0200 |
|---|---|---|
| committer | David Teigland <teigland@redhat.com> | 2009-06-18 20:42:42 +0200 |
| commit | c78a87d0a1fc885dfdbe21fd5e07787691dfb068 (patch) | |
| tree | 73f6056f87cd9183e04f3b9f6a4245876cf0cb23 /fs | |
| parent | dlm: Fix uninitialised variable warning in lock.c (diff) | |
| download | linux-c78a87d0a1fc885dfdbe21fd5e07787691dfb068.tar.xz linux-c78a87d0a1fc885dfdbe21fd5e07787691dfb068.zip | |
dlm: fix plock use-after-free
Fix a regression from the original addition of nfs lock support
586759f03e2e9031ac5589912a51a909ed53c30a. When a synchronous
(non-nfs) plock completes, the waiting thread will wake up and
free the op struct. This races with the user thread in
dev_write() which goes on to read the op's callback field to
check if the lock is async and needs a callback. This check
can happen on the freed op. The fix is to note the callback
value before the op can be freed.
Signed-off-by: David Teigland <teigland@redhat.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/dlm/plock.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c index 894a32d438d5..16f682e26c07 100644 --- a/fs/dlm/plock.c +++ b/fs/dlm/plock.c @@ -353,7 +353,7 @@ static ssize_t dev_write(struct file *file, const char __user *u, size_t count, { struct dlm_plock_info info; struct plock_op *op; - int found = 0; + int found = 0, do_callback = 0; if (count != sizeof(info)) return -EINVAL; @@ -366,21 +366,24 @@ static ssize_t dev_write(struct file *file, const char __user *u, size_t count, spin_lock(&ops_lock); list_for_each_entry(op, &recv_list, list) { - if (op->info.fsid == info.fsid && op->info.number == info.number && + if (op->info.fsid == info.fsid && + op->info.number == info.number && op->info.owner == info.owner) { + struct plock_xop *xop = (struct plock_xop *)op; list_del_init(&op->list); - found = 1; - op->done = 1; memcpy(&op->info, &info, sizeof(info)); + if (xop->callback) + do_callback = 1; + else + op->done = 1; + found = 1; break; } } spin_unlock(&ops_lock); if (found) { - struct plock_xop *xop; - xop = (struct plock_xop *)op; - if (xop->callback) + if (do_callback) dlm_plock_callback(op); else wake_up(&recv_wq); |