This is a note to let you know that I've just added the patch titled

scsi: bnx2fc: fix race condition in bnx2fc_get_host_stats()

to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: scsi-bnx2fc-fix-race-condition-in-bnx2fc_get_host_stats.patch and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Tue Apr 10 13:58:07 CEST 2018

From: Maurizio Lombardi mlombard@redhat.com Date: Wed, 24 May 2017 14:09:44 +0200 Subject: scsi: bnx2fc: fix race condition in bnx2fc_get_host_stats()

From: Maurizio Lombardi mlombard@redhat.com

[ Upstream commit c2dd893a3b0772d1c680e109b9d5715d7f73022b ]

If multiple tasks attempt to read the stats, it may happen that the start_req_done completion is re-initialized while still being used by another task, causing a list corruption.

This patch fixes the bug by adding a mutex to serialize the calls to bnx2fc_get_host_stats().

WARNING: at lib/list_debug.c:48 list_del+0x6e/0xa0() (Not tainted) Hardware name: PowerEdge R820 list_del corruption. prev->next should be ffff882035627d90, but was ffff884069541588

Pid: 40267, comm: perl Not tainted 2.6.32-642.3.1.el6.x86_64 #1 Call Trace: [<ffffffff8107c691>] ? warn_slowpath_common+0x91/0xe0 [<ffffffff8107c796>] ? warn_slowpath_fmt+0x46/0x60 [<ffffffff812ad16e>] ? list_del+0x6e/0xa0 [<ffffffff81547eed>] ? wait_for_common+0x14d/0x180 [<ffffffff8106c4a0>] ? default_wake_function+0x0/0x20 [<ffffffff81547fd3>] ? wait_for_completion_timeout+0x13/0x20 [<ffffffffa05410b1>] ? bnx2fc_get_host_stats+0xa1/0x280 [bnx2fc] [<ffffffffa04cf630>] ? fc_stat_show+0x90/0xc0 [scsi_transport_fc] [<ffffffffa04cf8b6>] ? show_fcstat_tx_frames+0x16/0x20 [scsi_transport_fc] [<ffffffff8137c647>] ? dev_attr_show+0x27/0x50 [<ffffffff8113b9be>] ? __get_free_pages+0xe/0x50 [<ffffffff812170e1>] ? sysfs_read_file+0x111/0x200 [<ffffffff8119a305>] ? vfs_read+0xb5/0x1a0 [<ffffffff8119b0b6>] ? fget_light_pos+0x16/0x50 [<ffffffff8119a651>] ? sys_read+0x51/0xb0 [<ffffffff810ee1fe>] ? __audit_syscall_exit+0x25e/0x290 [<ffffffff8100b0d2>] ? system_call_fastpath+0x16/0x1b

Signed-off-by: Maurizio Lombardi mlombard@redhat.com Acked-by: Chad Dupuis chad.dupuis@cavium.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/bnx2fc/bnx2fc.h | 1 + drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/scsi/bnx2fc/bnx2fc.h +++ b/drivers/scsi/bnx2fc/bnx2fc.h @@ -191,6 +191,7 @@ struct bnx2fc_hba { struct bnx2fc_cmd_mgr *cmd_mgr; spinlock_t hba_lock; struct mutex hba_mutex; + struct mutex hba_stats_mutex; unsigned long adapter_state; #define ADAPTER_STATE_UP 0 #define ADAPTER_STATE_GOING_DOWN 1 --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c @@ -641,15 +641,17 @@ static struct fc_host_statistics *bnx2fc if (!fw_stats) return NULL;

+ mutex_lock(&hba->hba_stats_mutex); + bnx2fc_stats = fc_get_host_stats(shost);

init_completion(&hba->stat_req_done); if (bnx2fc_send_stat_req(hba)) - return bnx2fc_stats; + goto unlock_stats_mutex; rc = wait_for_completion_timeout(&hba->stat_req_done, (2 * HZ)); if (!rc) { BNX2FC_HBA_DBG(lport, "FW stat req timed out\n"); - return bnx2fc_stats; + goto unlock_stats_mutex; } BNX2FC_STATS(hba, rx_stat2, fc_crc_cnt); bnx2fc_stats->invalid_crc_count += hba->bfw_stats.fc_crc_cnt; @@ -671,6 +673,9 @@ static struct fc_host_statistics *bnx2fc

memcpy(&hba->prev_stats, hba->stats_buffer, sizeof(struct fcoe_statistics_params)); + +unlock_stats_mutex: + mutex_unlock(&hba->hba_stats_mutex); return bnx2fc_stats; }

@@ -1303,6 +1308,7 @@ static struct bnx2fc_hba *bnx2fc_hba_cre } spin_lock_init(&hba->hba_lock); mutex_init(&hba->hba_mutex); + mutex_init(&hba->hba_stats_mutex);

hba->cnic = cnic;

Patches currently in stable-queue which might be from mlombard@redhat.com are

queue-3.18/scsi-bnx2fc-fix-race-condition-in-bnx2fc_get_host_stats.patch