debugfs: debugfs_lookup() should return NULL if not found (37ea7b63) · Commits · 戴 / test

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

fs/debugfs/inode.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -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;
		}

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