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 A3D913EEAC7; Tue, 21 Jul 2026 19:20:19 +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=1784661620; cv=none; b=BNg7ElkbTWWW/AdrsuRiqFSLNnFHrYt+f6SQ5DLXCFjX6ZwrIia01L9S19ESK6ArorpZk4y/x8Dn3LvXTd0JlQUTy6qN+0/ySPC14REVqqQHmbv3VpStBEJ9sqRA116oYvq+TwUjDOkYILqQotkj9XxoTjmSfyP6U/ZdtU+z+Xw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784661620; c=relaxed/simple; bh=twEqCyPRisVu+84AuEQVSxA3QG+v9OP4R1+75quBvt0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=abZfzInsq9KhtRXW+Uh0ChclxuRgP1nOw52YNw3MqJTHD0uluBtIs5c7TLt5Z7+gJpvtrP5MYUwvshvamFWJkV12htwaWZOTWxM6+1M5tscqWTEk8ptcym5063B/JyKpFKaZjy/bDGSIsxrZzvsKw5eW40WoXeE5mdvr6TYLm3Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KkstqI0L; 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="KkstqI0L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15DC61F000E9; Tue, 21 Jul 2026 19:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784661619; bh=UAbpgd5MHd0MmL45vnuSxPZX2zs2508quwVJowArV5w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KkstqI0Lc8g2gXh12ijiAxvslWZOlD4px9WPAs5gsTYoO81nI+Ztamw4fyXnblnZ4 N9a0Sk0x3EcvKENfRRKMbe74mZg9xCQoW+JeaNIlH4DSENDmXCARe+yQEmJijRURuO IR8RKyqtN7HipDZoYhNBFzaI0HIqFTCFpTsK+8C8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, NeilBrown , Tejun Heo , "Rafael J. Wysocki (Intel)" , Danilo Krummrich , Sasha Levin Subject: [PATCH 6.12 0133/1276] sysfs: clamp show() return value in sysfs_kf_read() Date: Tue, 21 Jul 2026 17:09:36 +0200 Message-ID: <20260721152449.078379568@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman [ Upstream commit 454257f6d124a92342dcbb7710c03dd6ef96c731 ] sysfs_kf_seq_show() defends against buggy show() callbacks that return larger than PAGE_SIZE by clamping the value and printing a warning. sysfs_kf_read(), the prealloc variant, has no such defense. The only current in-tree user of __ATTR_PREALLOC is drivers/md/md.c, whose show() callbacks are well-behaved, so this is hardening against future drivers doing foolish things and out-of-tree code doing even more foolish things. Cc: NeilBrown Cc: Tejun Heo Fixes: 2b75869bba67 ("sysfs/kernfs: allow attributes to request write buffer be pre-allocated.") Assisted-by: gregkh_clanker_t1000 Reviewed-by: Rafael J. Wysocki (Intel) Reviewed-by: Danilo Krummrich Link: https://patch.msgid.link/2026052000-drove-unicycle-d61b@gregkh Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- fs/sysfs/file.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index d1995e2d6c943a..c76a8b81102bf9 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -114,6 +114,10 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf, len = ops->show(kobj, of->kn->priv, buf); if (len < 0) return len; + if (len >= (ssize_t)PAGE_SIZE) { + printk("fill_read_buffer: %pS returned bad count\n", ops->show); + len = PAGE_SIZE - 1; + } if (pos) { if (len <= pos) return 0; -- 2.53.0