From: Nicolai Stange Date: Tue, 24 May 2016 11:08:54 +0000 (+0200) Subject: debugfs: open_proxy_open(): avoid double fops release X-Git-Tag: v4.7-rc4~7^2~7 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=75f0b68b75dabb3ff551440163fd67b3fc62901a;p=karo-tx-linux.git debugfs: open_proxy_open(): avoid double fops release Debugfs' open_proxy_open(), the ->open() installed at all inodes created through debugfs_create_file_unsafe(), - grabs a reference to the original file_operations instance passed to debugfs_create_file_unsafe() via fops_get(), - installs it at the file's ->f_op by means of replace_fops() - and calls fops_put() on it. Since the semantics of replace_fops() are such that the reference's ownership is transferred, the subsequent fops_put() will result in a double release when the file is eventually closed. Currently, this is not an issue since fops_put() basically does a module_put() on the file_operations' ->owner only and there don't exist any modules calling debugfs_create_file_unsafe() yet. This is expected to change in the future though, c.f. commit c64688081490 ("debugfs: add support for self-protecting attribute file fops"). Remove the call to fops_put() from open_proxy_open(). Fixes: 9fd4dcece43a ("debugfs: prevent access to possibly dead file_operations at file open") Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index d1ec80331414..592059f88e04 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -127,7 +127,6 @@ static int open_proxy_open(struct inode *inode, struct file *filp) r = real_fops->open(inode, filp); out: - fops_put(real_fops); debugfs_use_file_finish(srcu_idx); return r; }