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authorXiubo Li <xiubli@redhat.com>2022-11-17 03:57:53 +0100
committerIlya Dryomov <idryomov@gmail.com>2023-01-02 12:27:25 +0100
commit8e1858710d9a71d88acd922f2e95d1eddb90eea0 (patch)
tree478a0dfc7713b89e895ea5ac7e8ed5020b782107 /fs
parentceph: switch to vfs_inode_has_locks() to fix file lock bug (diff)
downloadlinux-8e1858710d9a71d88acd922f2e95d1eddb90eea0.tar.xz
linux-8e1858710d9a71d88acd922f2e95d1eddb90eea0.zip
ceph: avoid use-after-free in ceph_fl_release_lock()
When ceph releasing the file_lock it will try to get the inode pointer from the fl->fl_file, which the memory could already be released by another thread in filp_close(). Because in VFS layer the fl->fl_file doesn't increase the file's reference counter. Will switch to use ceph dedicate lock info to track the inode. And in ceph_fl_release_lock() we should skip all the operations if the fl->fl_u.ceph.inode is not set, which should come from the request file_lock. And we will set fl->fl_u.ceph.inode when inserting it to the inode lock list, which is when copying the lock. Link: https://tracker.ceph.com/issues/57986 Signed-off-by: Xiubo Li <xiubli@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/ceph/locks.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index 6b3b8c299c17..9c8dc8a55e7e 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -34,18 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
{
struct inode *inode = file_inode(dst->fl_file);
atomic_inc(&ceph_inode(inode)->i_filelock_ref);
+ dst->fl_u.ceph.inode = igrab(inode);
}
+/*
+ * Do not use the 'fl->fl_file' in release function, which
+ * is possibly already released by another thread.
+ */
static void ceph_fl_release_lock(struct file_lock *fl)
{
- struct inode *inode = file_inode(fl->fl_file);
- struct ceph_inode_info *ci = ceph_inode(inode);
+ struct inode *inode = fl->fl_u.ceph.inode;
+ struct ceph_inode_info *ci;
+
+ /*
+ * If inode is NULL it should be a request file_lock,
+ * nothing we can do.
+ */
+ if (!inode)
+ return;
+
+ ci = ceph_inode(inode);
if (atomic_dec_and_test(&ci->i_filelock_ref)) {
/* clear error when all locks are released */
spin_lock(&ci->i_ceph_lock);
ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
spin_unlock(&ci->i_ceph_lock);
}
+ fl->fl_u.ceph.inode = NULL;
+ iput(inode);
}
static const struct file_lock_operations ceph_fl_lock_ops = {