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authorNicolai Stange <nicstange@gmail.com>2016-05-24 13:08:53 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-15 13:56:35 +0200
commitb10e3e90485e32e4cea9e35d2295ee7bffaeff73 (patch)
tree99aeebe65cb41e45077f9bc6f3f500214dbe742a /fs/debugfs
parentkernel/kcov: unproxify debugfs file's fops (diff)
downloadlinux-b10e3e90485e32e4cea9e35d2295ee7bffaeff73.tar.xz
linux-b10e3e90485e32e4cea9e35d2295ee7bffaeff73.zip
debugfs: full_proxy_open(): free proxy on ->open() failure
Debugfs' full_proxy_open(), the ->open() installed at all inodes created through debugfs_create_file(), - grabs a reference to the original struct file_operations instance passed to debugfs_create_file(), - dynamically allocates a proxy struct file_operations instance wrapping the original - and installs this at the file's ->f_op. Afterwards, it calls the original ->open() and passes its return value back to the VFS layer. Now, if that return value indicates failure, the VFS layer won't ever call ->release() and thus, neither the reference to the original file_operations nor the memory for the proxy file_operations will get released, i.e. both are leaked. Upon failure of the original fops' ->open(), undo the proxy installation. That is: - Set the struct file ->f_op to what it had been when full_proxy_open() was entered. - Drop the reference to the original file_operations. - Free the memory holding the proxy file_operations. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/debugfs')
-rw-r--r--fs/debugfs/file.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 9c1c9a01b7e5..d1ec80331414 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -262,8 +262,10 @@ static int full_proxy_open(struct inode *inode, struct file *filp)
if (real_fops->open) {
r = real_fops->open(inode, filp);
-
- if (filp->f_op != proxy_fops) {
+ if (r) {
+ replace_fops(filp, d_inode(dentry)->i_fop);
+ goto free_proxy;
+ } else if (filp->f_op != proxy_fops) {
/* No protection against file removal anymore. */
WARN(1, "debugfs file owner replaced proxy fops: %pd",
dentry);