From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9020E1D0434; Wed, 2 Oct 2024 13:25:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727875515; cv=none; b=ohI03U0BSIXxy+CEo6JoeGSW3foLI+edZbAmeHHO/z8aGtepaYSVrNiFsx2WjYsWlacgTNHOydsBMxs/wyShbVXyebsEacZTtpBvLTMLJ8yXx52ueFPbJgicbEzIfx6KHAZlpLlSlyVJ7Bvy2DU/RzqmopEiAl8LwO5ehZoF97U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727875515; c=relaxed/simple; bh=r0BAaIYT2zCvb/bKvlDpv/vNPGAXUOwiJ35Nl+CiKEo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tzeBMM+adbioz72Dqhn0FPOoC4ajZSUFfLrXud4JjHMt1XgBPsJB85khqkLKG5oJ7SY1dRN8ZJIGLXoWWEt+Ss6UlgntFzCHbyLph+xLiqSMzt6711b5FFRn1zwFSSBjayn56OOmnPbWH0BkO4/AnIPFh67H0glQG1npZhQ+ni8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eIK0gkYZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eIK0gkYZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3212C4CEC5; Wed, 2 Oct 2024 13:25:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727875515; bh=r0BAaIYT2zCvb/bKvlDpv/vNPGAXUOwiJ35Nl+CiKEo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eIK0gkYZ1ac1t2TRr2LojfI5qTHrrEPMmt3BnANnkKhCGCUoi5rUqYD5k/k1pU74M 4YMPZRvG00dpMwDlmoBMpcmxzsuSttbNoFoIDX0GFaEMxXj0+dgxs0I1ySPq0Ik985 t4ssi4nf/74xR0FlnxbfLDtrE6TSmD9+m7vKGS2w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Jens Axboe , Sasha Levin Subject: [PATCH 6.11 128/695] block, bfq: fix uaf for accessing waker_bfqq after splitting Date: Wed, 2 Oct 2024 14:52:06 +0200 Message-ID: <20241002125827.588275967@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125822.467776898@linuxfoundation.org> References: <20241002125822.467776898@linuxfoundation.org> User-Agent: quilt/0.67 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 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Kuai [ Upstream commit 1ba0403ac6447f2d63914fb760c44a3b19c44eaf ] After commit 42c306ed7233 ("block, bfq: don't break merge chain in bfq_split_bfqq()"), if the current procress is the last holder of bfqq, the bfqq can be freed after bfq_split_bfqq(). Hence recored the bfqq and then access bfqq->waker_bfqq may trigger UAF. What's more, the waker_bfqq may in the merge chain of bfqq, hence just recored waker_bfqq is still not safe. Fix the problem by adding a helper bfq_waker_bfqq() to check if bfqq->waker_bfqq is in the merge chain, and current procress is the only holder. Fixes: 42c306ed7233 ("block, bfq: don't break merge chain in bfq_split_bfqq()") Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20240909134154.954924-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/bfq-iosched.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index ca766b7d5560e..8533e92c5d9ef 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6825,6 +6825,31 @@ static void bfq_prepare_request(struct request *rq) rq->elv.priv[0] = rq->elv.priv[1] = NULL; } +static struct bfq_queue *bfq_waker_bfqq(struct bfq_queue *bfqq) +{ + struct bfq_queue *new_bfqq = bfqq->new_bfqq; + struct bfq_queue *waker_bfqq = bfqq->waker_bfqq; + + if (!waker_bfqq) + return NULL; + + while (new_bfqq) { + if (new_bfqq == waker_bfqq) { + /* + * If waker_bfqq is in the merge chain, and current + * is the only procress. + */ + if (bfqq_process_refs(waker_bfqq) == 1) + return NULL; + break; + } + + new_bfqq = new_bfqq->new_bfqq; + } + + return waker_bfqq; +} + /* * If needed, init rq, allocate bfq data structures associated with * rq, and increment reference counters in the destination bfq_queue @@ -6886,7 +6911,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) /* If the queue was seeky for too long, break it apart. */ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq) && !bic->bfqq_data[a_idx].stably_merged) { - struct bfq_queue *old_bfqq = bfqq; + struct bfq_queue *waker_bfqq = bfq_waker_bfqq(bfqq); /* Update bic before losing reference to bfqq */ if (bfq_bfqq_in_large_burst(bfqq)) @@ -6906,7 +6931,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) bfqq_already_existing = true; if (!bfqq_already_existing) { - bfqq->waker_bfqq = old_bfqq->waker_bfqq; + bfqq->waker_bfqq = waker_bfqq; bfqq->tentative_waker_bfqq = NULL; /* @@ -6916,7 +6941,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) * woken_list of the waker. See * bfq_check_waker for details. */ - if (bfqq->waker_bfqq) + if (waker_bfqq) hlist_add_head(&bfqq->woken_list_node, &bfqq->waker_bfqq->woken_list); } -- 2.43.0