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 1B30C3C1976; Fri, 24 Apr 2026 13:40:06 +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=1777038007; cv=none; b=acnq9otI2Scod27I6i5Zq5rG4rVRhCFhs3jjiTyvtBmzJkVh0vaPHXz0QhSXS6Vb6ctIaqtGn62zuHp0y90oImai0rItxhmoCXycI5+IeOlb/t9tO9Z6XOmmOJNmFXbX0bqN1c6ZRCimrReL4U/qp0Nq26n8Dyn8bqBQJLI+NrY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038007; c=relaxed/simple; bh=QRrgYW9vx81BgQKxj8rMk3Ltmrpy4BYZwF371BJWSAQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NfBJzWs0b5IZIA3QrwGK3t4to3iyUqPHpruUCAXPrXUcDhe/GvCmiS90lH6nlCfADbzNrzH/O0xXz8w1BMdr6UMN81T452Bllk7Yd5KiegLYUVjtkLbTtUHhylugm+GqxqiKNaone6+87AySYNy/CeMtvmNg1tM6O+0XF824X64= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Lsoyka37; 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="Lsoyka37" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7214CC19425; Fri, 24 Apr 2026 13:40:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038006; bh=QRrgYW9vx81BgQKxj8rMk3Ltmrpy4BYZwF371BJWSAQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lsoyka37z1M/C/vMgWOpKOGjXFmm9Lz6/hod/a5ao6ZPZEIGLaoPRto0woiqB2iZR M7lHgmgzFmY+whVaDL+Q9qOkeqz1eMV4/EZ4yayusZe6vhNWDScq+n0mDgIXsaHLto P6MBkHqljc3r1/Jw3lNniv/tC9ETcXpWDuMAsDFo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mingzhe Zou , Coly Li , Jens Axboe Subject: [PATCH 6.6 121/166] bcache: fix cached_dev.sb_bio use-after-free and crash Date: Fri, 24 Apr 2026 15:30:35 +0200 Message-ID: <20260424132558.107018879@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132532.812258529@linuxfoundation.org> References: <20260424132532.812258529@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mingzhe Zou commit fec114a98b8735ee89c75216c45a78e28be0f128 upstream. In our production environment, we have received multiple crash reports regarding libceph, which have caught our attention: ``` [6888366.280350] Call Trace: [6888366.280452] blk_update_request+0x14e/0x370 [6888366.280561] blk_mq_end_request+0x1a/0x130 [6888366.280671] rbd_img_handle_request+0x1a0/0x1b0 [rbd] [6888366.280792] rbd_obj_handle_request+0x32/0x40 [rbd] [6888366.280903] __complete_request+0x22/0x70 [libceph] [6888366.281032] osd_dispatch+0x15e/0xb40 [libceph] [6888366.281164] ? inet_recvmsg+0x5b/0xd0 [6888366.281272] ? ceph_tcp_recvmsg+0x6f/0xa0 [libceph] [6888366.281405] ceph_con_process_message+0x79/0x140 [libceph] [6888366.281534] ceph_con_v1_try_read+0x5d7/0xf30 [libceph] [6888366.281661] ceph_con_workfn+0x329/0x680 [libceph] ``` After analyzing the coredump file, we found that the address of dc->sb_bio has been freed. We know that cached_dev is only freed when it is stopped. Since sb_bio is a part of struct cached_dev, rather than an alloc every time. If the device is stopped while writing to the superblock, the released address will be accessed at endio. This patch hopes to wait for sb_write to complete in cached_dev_free. It should be noted that we analyzed the cause of the problem, then tell all details to the QWEN and adopted the modifications it made. Signed-off-by: Mingzhe Zou Fixes: cafe563591446 ("bcache: A block layer cache") Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Coly Li Link: https://patch.msgid.link/20260322134102.480107-1-colyli@fnnas.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/md/bcache/super.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1367,6 +1367,13 @@ static void cached_dev_free(struct closu mutex_unlock(&bch_register_lock); + /* + * Wait for any pending sb_write to complete before free. + * The sb_bio is embedded in struct cached_dev, so we must + * ensure no I/O is in progress. + */ + closure_sync(&dc->sb_write); + if (dc->sb_disk) put_page(virt_to_page(dc->sb_disk));