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 2E9F83B95E0; Tue, 21 Jul 2026 21:43:18 +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=1784670199; cv=none; b=B/HpH4llOTUyNwfwg4r0VHZpaIeQ88FQ1EhJDikryGdvv9txfLTJVZLRKcZr/XkJBynL7LRGLZQNq4Z3XCSPWQ51RHLJ0Sh+Prpz2fkKIAGKrTZq5piqAxtabDDqECXtjMVB7srjEEDSOrdcYZW3F1wPnBs2upH/4zDlwHdXOG0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670199; c=relaxed/simple; bh=jaMUqvCuk0Nrjlm++pTahXc+mNnNtIvf0owUqTN0KWM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gWS+GfwOv79k7m74EgnVuFpfQwc6iVnR+Pi8XzpFmJSl3yjidi39FfwtdBSq994SK7cgAhdQfl5ZdipnZO1Zpx9QXswcV1mywdmMwfpcUxSif24b+iRaVSLodtSSWb7yIgfX30Hxi4/UodXtTYD1X8StEd3I3pR37CaxbTtc7mA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XIL7sWJV; 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="XIL7sWJV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93B2C1F00A3A; Tue, 21 Jul 2026 21:43:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670198; bh=mB4bEa8XQoecvmJS8ZXVosDdW9aYobm+wd2v37MbVVE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XIL7sWJVNH2FuBRFWUnbZITTn/pPF5X/75NAhREcxMxC7sSVa1Lg5We2JiiXlwJQu RDYmi8vjnPK5wTDh0Rn4m2kSbI6LrSPjVrjxCFlmMZdkOZQ2juVXHoRgsb4bvupZRv QsubJFsYOng/HRI8VYa02ncw4r3S3DoaxKQt/Jqw= 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 6.1 0799/1067] proc: only bump parent nlink when registering directories Date: Tue, 21 Jul 2026 17:23:20 +0200 Message-ID: <20260721152442.434503543@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@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 6.1-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; } @@ -400,7 +402,6 @@ 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; @@ -699,6 +700,8 @@ 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--; } /* @@ -724,8 +727,6 @@ 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); @@ -784,8 +785,6 @@ 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);