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debugfs: debugfs_lookup() should return NULL if not found

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Lots of callers of debugfs_lookup() were just checking NULL to see if
the file/directory was found or not.  By changing this in ff9fb72bc0
("debugfs: return error values, not NULL") we caused some subsystems to
easily crash.

Fixes: ff9fb72bc0 ("debugfs: return error values, not NULL")
Reported-by: syzbot+b382ba6a802a3d242790@syzkaller.appspotmail.com
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2019-01-30 12:37:35 +01:00
parent ff9fb72bc0
commit 37ea7b630a
1 changed files with 5 additions and 5 deletions
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10
fs/debugfs/inode.c
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@ -254,8 +254,8 @@ MODULE_ALIAS_FS("debugfs");
* @parent: a pointer to the parent dentry of the file.
*
* This function will return a pointer to a dentry if it succeeds. If the file
* doesn't exist or an error occurs, %ERR_PTR(-ERROR) will be returned. The
* returned dentry must be passed to dput() when it is no longer needed.
* doesn't exist or an error occurs, %NULL will be returned. The returned
* dentry must be passed to dput() when it is no longer needed.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
@ -265,17 +265,17 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
struct dentry *dentry;
if (IS_ERR(parent))
return parent;
return NULL;
if (!parent)
parent = debugfs_mount->mnt_root;
dentry = lookup_one_len_unlocked(name, parent, strlen(name));
if (IS_ERR(dentry))
return dentry;
return NULL;
if (!d_really_is_positive(dentry)) {
dput(dentry);
return ERR_PTR(-EINVAL);
return NULL;
}
return dentry;
}