From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3ADE638B7B0; Fri, 12 Jun 2026 15:30:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781278235; cv=none; b=sjZo5nJYj8YUpQm7RACASDS7/E5voepcsWOxrycU0frf8d7oPfcbdsJoPq/ofPtHQWf4yviPvypjlbXbN1srn35Y4jeX8WDvz18aAQtsjdftm5Yw28y2ZB2Zr7FV9uLgn6CEQ4NfK1tqiAlisC+l80osReNpU2wWS5VNb6Lxs94= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781278235; c=relaxed/simple; bh=cVVAyTXsZJyiSC5hpQfsjij1dyemK+YG/UgrwEcyC9I=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Twf8Mmr5d8D6jys+mEdq0YRgTpjs+PxsawA7yTMphCUG86Wo+03br5sj1ZasLEkHq3Myx0Hel8NbrTjOuG6p1GTRRHLDnliucZrq61LkUCIe1++rzszfauo3HiR/4XjTZSiaocbAeJSnbR58L9lL0kn44PyQI8O0pPewE9RX29Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IkP21ZBY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IkP21ZBY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A6BD1F00A3F; Fri, 12 Jun 2026 15:30:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781278233; bh=/Zhwwy0u9Y8ZgnqS3Nt6scpfw4vg3nu8ME6rn1XUGgM=; h=From:To:Cc:Subject:Date; b=IkP21ZBYjZkYu+RP1LddXB5XY/hQZ8DPSBl++eaAvsCsfDIDXszW5eCOIEZXQ3NcN fNr2wuq+jbEkn9UdX87evfptf2MMXyOlsoJOKN1OfsfkhVP9MSGWCNcRROfQElW3e2 KPmiiO8rOaKTVgk4nRoi8GU5V+1zLnKUHAlThnpxeae5UssdyNEeTpIIIaZ6CNayL2 xTZ4sGZ1rE6dZcWhVrGLNnkVSQ9pur5SdMaK3xd/yUwoCqT/9HxI9vNBKRAveLVyR6 RYg5IFVc0z+bmbtkfSDG4YSDCIiy1A2M09L/pekoaAh2+K0dw5Kgr1Ig4NKgOdoL+0 poLP/NIS0vOVg== From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= To: Andrew Morton Cc: Alexey Dobriyan , Christian Brauner , Jan Kara , Wei Yang , Zijie Wang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] proc: only bump parent nlink when registering directories Date: Fri, 12 Jun 2026 15:30:31 +0000 Message-ID: <20260612153031.536525-1-kwilczynski@kernel.org> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit proc_register() increments the parent directory's link count for every entry it registers, while remove_proc_entry() and remove_proc_subtree() decrement it only when the removed entry is a directory. Regular files thus inflate the parent's count while they exist, and leak one link permanently on every create and remove cycle. For example, /proc/bus/pci/00 with twenty-two device files and no subdirectories reports nlink 24 instead of 2, and SR-IOV VF enable and disable cycles, each creating and removing the VF config space entries under /proc/bus/pci/, inflate the link count of that directory without bound. Before commit e06689bf5701 ("proc: change ->nlink under proc_subdir_lock"), the increment lived in proc_mkdir_data() and proc_create_mount_point(), and was therefore applied only to directories. Moving it into proc_register() to bring it under proc_subdir_lock dropped the S_ISDIR check. Thus, increment the parent link count only for directories, matching the decrements in remove_proc_entry() and remove_proc_subtree(). Fixes: e06689bf5701 ("proc: change ->nlink under proc_subdir_lock") Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Krzysztof Wilczyński --- fs/proc/generic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 8bb81e58c9d8..3ac825c79313 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -404,7 +404,8 @@ struct proc_dir_entry *proc_register(struct proc_dir_entry *dir, write_unlock(&proc_subdir_lock); goto out_free_inum; } - dir->nlink++; + if (S_ISDIR(dp->mode)) + dir->nlink++; write_unlock(&proc_subdir_lock); return dp; -- 2.54.0