From patchwork Wed Dec 16 17:38:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 557615 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 4E4BC1401AD; Thu, 17 Dec 2015 04:43:35 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1a9G6q-0001PY-RH; Wed, 16 Dec 2015 17:43:28 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1a9G46-00009a-1N for kernel-team@lists.ubuntu.com; Wed, 16 Dec 2015 17:40:38 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1a9G45-0006WN-Iy; Wed, 16 Dec 2015 17:40:37 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1a9G43-0005J6-BS; Wed, 16 Dec 2015 09:40:35 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.19.y-ckt 086/128] target: Fix race for SCF_COMPARE_AND_WRITE_POST checking Date: Wed, 16 Dec 2015 09:38:46 -0800 Message-Id: <1450287568-19808-87-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1450287568-19808-1-git-send-email-kamal@canonical.com> References: <1450287568-19808-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Cc: Sagi Grimberg , Kamal Mostafa , Nicholas Bellinger X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.19.8-ckt12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 057085e522f8bf94c2e691a5b76880f68060f8ba upstream. This patch addresses a race + use after free where the first stage of COMPARE_AND_WRITE in compare_and_write_callback() is rescheduled after the backend sends the secondary WRITE, resulting in second stage compare_and_write_post() callback completing in target_complete_ok_work() before the first can return. Because current code depends on checking se_cmd->se_cmd_flags after return from se_cmd->transport_complete_callback(), this results in first stage having SCF_COMPARE_AND_WRITE_POST set, which incorrectly falls through into second stage CAW processing code, eventually triggering a NULL pointer dereference due to use after free. To address this bug, pass in a new *post_ret parameter into se_cmd->transport_complete_callback(), and depend upon this value instead of ->se_cmd_flags to determine when to return or fall through into ->queue_status() code for CAW. Cc: Sagi Grimberg Signed-off-by: Nicholas Bellinger Signed-off-by: Kamal Mostafa --- drivers/target/target_core_sbc.c | 13 +++++++++---- drivers/target/target_core_transport.c | 14 ++++++++------ include/target/target_core_base.h | 2 +- 3 files changed, 18 insertions(+), 11 deletions(-) diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 48de053..384f20c 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -299,7 +299,8 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o return 0; } -static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success) +static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success, + int *post_ret) { unsigned char *buf, *addr; struct scatterlist *sg; @@ -363,7 +364,8 @@ sbc_execute_rw(struct se_cmd *cmd) cmd->data_direction); } -static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) +static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, + int *post_ret) { struct se_device *dev = cmd->se_dev; @@ -373,8 +375,10 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) * sent to the backend driver. */ spin_lock_irq(&cmd->t_state_lock); - if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) + if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) { cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; + *post_ret = 1; + } spin_unlock_irq(&cmd->t_state_lock); /* @@ -386,7 +390,8 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) return TCM_NO_SENSE; } -static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success) +static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success, + int *post_ret) { struct se_device *dev = cmd->se_dev; struct scatterlist *write_sg = NULL, *sg; diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index f786de0..a738637 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1596,7 +1596,7 @@ bool target_stop_cmd(struct se_cmd *cmd, unsigned long *flags) void transport_generic_request_failure(struct se_cmd *cmd, sense_reason_t sense_reason) { - int ret = 0; + int ret = 0, post_ret = 0; pr_debug("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08x" " CDB: 0x%02x\n", cmd, cmd->se_tfo->get_task_tag(cmd), @@ -1619,7 +1619,7 @@ void transport_generic_request_failure(struct se_cmd *cmd, */ if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) && cmd->transport_complete_callback) - cmd->transport_complete_callback(cmd, false); + cmd->transport_complete_callback(cmd, false, &post_ret); switch (sense_reason) { case TCM_NON_EXISTENT_LUN: @@ -1974,11 +1974,13 @@ static void target_complete_ok_work(struct work_struct *work) */ if (cmd->transport_complete_callback) { sense_reason_t rc; + bool caw = (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE); + bool zero_dl = !(cmd->data_length); + int post_ret = 0; - rc = cmd->transport_complete_callback(cmd, true); - if (!rc && !(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE_POST)) { - if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) && - !cmd->data_length) + rc = cmd->transport_complete_callback(cmd, true, &post_ret); + if (!rc && !post_ret) { + if (caw && zero_dl) goto queue_rsp; return; diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 985ca4c..08f581b 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -524,7 +524,7 @@ struct se_cmd { sense_reason_t (*execute_cmd)(struct se_cmd *); sense_reason_t (*execute_rw)(struct se_cmd *, struct scatterlist *, u32, enum dma_data_direction); - sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool); + sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool, int *); unsigned char *t_task_cdb; unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE];