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 98FF325B0AB; Tue, 21 Jul 2026 22:20:31 +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=1784672432; cv=none; b=PPSyr63IDbBUvFLzm6Jeu0Cwk6/UQl2EIQPsRRAIvB8jZBHZ9FEfIKP3VaZ3/POOW2eRgFt5fADoLVmDUSh5SiizzGOlXCRfJIwV+bN9a8V8/Rcu+Xyg4nbu7tq1Bg6HAagA8qAs/gCSC/e5C/K7DVksdaJVWgLdZH295Igrabc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784672432; c=relaxed/simple; bh=GeJr12G9b5LEnv4uBELRFjDhzG/Npuhfx6emT24UG8M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jTOe7M3BY6WXKwQCdi+b0oln+SK7z26F7Xf9qsRTx0g2jdzu5W+lC6fuPHhsJaI4Ca/OCljDjLHBCop0x39x4R05uH0aBCdk6hvis2ZOMEacUk/YhbiLGLdqCO7kRCFXefW1D9KupWRvd6wQnIcR66p7HYaLufDV8XdMNYQDYH4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CUs6TKMb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CUs6TKMb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B82861F000E9; Tue, 21 Jul 2026 22:20:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784672431; bh=O4uLLCA5dBAyE7kzXYqeM6kqLt3Hv+NKdf2mmEpyKdY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CUs6TKMbjfArK43WokjAhpGYeYVjEcGDJPr4kQb+wvf8n0XrFSu8oqyJkygLG9maX TtULiVR07+FP8Cb/y+Rw6QG/3l1cUvHVL7/D2/R8R9oe5EsGb75CYIo0eTLlmdD1BJ KLIN+oKthAvH78AkCqmkNXe4+AJYEEEfJl2Mr4cE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , "Christian Brauner (Amutable)" Subject: [PATCH 5.15 621/843] proc: only bump parent nlink when registering directories Date: Tue, 21 Jul 2026 17:24:16 +0200 Message-ID: <20260721152420.029211767@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Krzysztof Wilczyński commit 16b02eb4b9b272c221255c20d34ccd5db53a3ed3 upstream. 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, move the nlink accounting into pde_subdir_insert() and pde_erase(), only updating it for directories in both, so the link count is always changed together with the directory entry itself. Fixes: e06689bf5701 ("proc: change ->nlink under proc_subdir_lock") Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Krzysztof Wilczyński Link: https://patch.msgid.link/20260613211005.921692-1-kwilczynski@kernel.org Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman --- fs/proc/generic.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -112,6 +112,8 @@ static bool pde_subdir_insert(struct pro /* Add new node and rebalance tree. */ rb_link_node(&de->subdir_node, parent, new); rb_insert_color(&de->subdir_node, root); + if (S_ISDIR(de->mode)) + dir->nlink++; return true; } @@ -378,7 +380,6 @@ struct proc_dir_entry *proc_register(str write_unlock(&proc_subdir_lock); goto out_free_inum; } - dir->nlink++; write_unlock(&proc_subdir_lock); return dp; @@ -692,6 +693,8 @@ static void pde_erase(struct proc_dir_en { rb_erase(&pde->subdir_node, &parent->subdir); RB_CLEAR_NODE(&pde->subdir_node); + if (S_ISDIR(pde->mode)) + parent->nlink--; } /* @@ -717,8 +720,6 @@ void remove_proc_entry(const char *name, de = NULL; } else { pde_erase(de, parent); - if (S_ISDIR(de->mode)) - parent->nlink--; } } write_unlock(&proc_subdir_lock); @@ -777,8 +778,6 @@ int remove_proc_subtree(const char *name continue; } next = de->parent; - if (S_ISDIR(de->mode)) - next->nlink--; write_unlock(&proc_subdir_lock); proc_entry_rundown(de);