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 5E4BC530DF7; Wed, 9 Sep 2026 14:20:01 +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=1788963602; cv=none; b=DTRgWnE0rkOWgk3ag0hJMHT9vFfTRTk1Tim1Em3WBpVk50FVAdO/qWyvNmfurtPLarM3S6G9FxD4FhO/VAT7pmPHjEt4Fco2y9JgdVuO3vQ1+axO4QbCnyLPHPjQTUVdFf2TfV0nF9MOG3WFKH9MgjISzeTyBH9XQ9vAPED88lw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788963602; c=relaxed/simple; bh=GikECVzsNGqIloKykOCqWxSJlmW9yR4mUlcwtG6A/Ho=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WT04mrKj8QaDqoxPFpVAzxl48mukIvy0sNJwiPFyBC3GghS7BD6dv/jz5hpgB6oCHnt5o5obL0TH3hxVzcHL713OQ7E7W0kCdXwfaPPbQOICidjUCULqqEe3qMCw3tSrkzETaKxdaZtoudSGiuZLeamSSYVGy1IIqZ8szMsPxu4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZEC9+16T; 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="ZEC9+16T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A960F1F00A3A; Wed, 9 Sep 2026 14:20:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788963601; bh=PoabeC/gyklxyvdOcjhHT/u6gwS94wKyx8NGy7/ctHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZEC9+16TRpWm77oxcq90qGXtDsUMHaH7Nktdj9rsNQBd0BRGBS7mCLimFqoz9d6+L De1Y8qFfa9XrrvMFtwqCj9h4o+izhmcEXKxQ232Bdi/FAgbY9NQGIr+h31XehzMXt4 o97+i6t6sVDOFDk54cxbWgJ6/c282mIggEatfOZI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bryam Vargas , Alison Schofield Subject: [PATCH 6.18 118/583] nvdimm/btt: reject an arena whose nfree is below the lane count Date: Wed, 9 Sep 2026 15:36:43 +0200 Message-ID: <20260909134242.217206128@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134237.773280130@linuxfoundation.org> References: <20260909134237.773280130@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-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bryam Vargas commit 6a1f2e5ed9267ca19187038ac635393c165213ac upstream. The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write. btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant. Fixes: 5212e11fde4d ("nd_btt: atomic sector updates") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Alison Schofield Tested-by: Alison Schofield Link: https://patch.msgid.link/20260620-b4-disp-88b2514b-v1-1-3834e707d232@proton.me Signed-off-by: Alison Schofield Signed-off-by: Greg Kroah-Hartman --- drivers/nvdimm/btt.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/nvdimm/btt.c +++ b/drivers/nvdimm/btt.c @@ -885,6 +885,14 @@ static int discover_arenas(struct btt *b arena->external_lba_start = cur_nlba; parse_arena_meta(arena, super, cur_off); + if (arena->nfree < btt->nd_region->num_lanes) { + dev_err(to_dev(arena), + "nfree %u smaller than lane count %d\n", + arena->nfree, btt->nd_region->num_lanes); + ret = -ENODEV; + goto out; + } + ret = log_set_indices(arena); if (ret) { dev_err(to_dev(arena),