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author | Nicolai Stange <nicstange@gmail.com> | 2016-05-24 13:08:54 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-06-15 04:56:35 -0700 |
commit | 75f0b68b75dabb3ff551440163fd67b3fc62901a (patch) | |
tree | 244a5ab2bfd5823bcfd9bbe15c3dff3c8491588c /fs/debugfs/file.c | |
parent | b10e3e90485e32e4cea9e35d2295ee7bffaeff73 (diff) | |
download | blackbird-op-linux-75f0b68b75dabb3ff551440163fd67b3fc62901a.tar.gz blackbird-op-linux-75f0b68b75dabb3ff551440163fd67b3fc62901a.zip |
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 <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/debugfs/file.c')
-rw-r--r-- | fs/debugfs/file.c | 1 |
1 files changed, 0 insertions, 1 deletions
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; } |