From ee5492fd88cfc079c19fbeac78e9e53b7f6c04f3 Mon Sep 17 00:00:00 2001 From: Chengfeng Ye Date: Wed, 11 Feb 2026 19:13:29 +0000 Subject: fbnic: close fw_log race between users and teardown Fixes a theoretical race on fw_log between the teardown path and fw_log write functions. fw_log is written inside fbnic_fw_log_write() and can be reached from the mailbox handler fbnic_fw_msix_intr(), but fw_log is freed before IRQ/MBX teardown during cleanup, resulting in a potential data race of dereferencing a freed/null variable. Possible Interleaving Scenario: CPU0: fbnic_fw_msix_intr() // Entry fbnic_fw_log_write() if (fbnic_fw_log_ready()) // true ... preempt ... CPU1: fbnic_remove() // Entry fbnic_fw_log_free() vfree(log->data_start); log->data_start = NULL; CPU0: continues, walks log->entries or writes to log->data_start The initialization also has an incorrect order problem, as the fw_log is currently allocated after MBX setup during initialization. Fix the problems by adjusting the synchronization order to put initialization in place before the mailbox is enabled, and not cleared until after the mailbox has been disabled. Fixes: ecc53b1b46c89 ("eth: fbnic: Enable firmware logging") Signed-off-by: Chengfeng Ye Link: https://patch.msgid.link/20260211191329.530886-1-dg573847474@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c | 3 --- drivers/net/ethernet/meta/fbnic/fbnic_pci.c | 19 ++++++++++++------- 2 files changed, 12 insertions(+), 10 deletions(-) diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c index 85a883dba385..d8a9a7d7c237 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c +++ b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c @@ -51,8 +51,6 @@ int fbnic_fw_log_init(struct fbnic_dev *fbd) log->data_start = data; log->data_end = data + FBNIC_FW_LOG_SIZE; - fbnic_fw_log_enable(fbd, true); - return 0; } @@ -63,7 +61,6 @@ void fbnic_fw_log_free(struct fbnic_dev *fbd) if (!fbnic_fw_log_ready(fbd)) return; - fbnic_fw_log_disable(fbd); INIT_LIST_HEAD(&log->entries); log->size = 0; vfree(log->data_start); diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_pci.c b/drivers/net/ethernet/meta/fbnic/fbnic_pci.c index 6f9389748a7d..3fa9d1910daa 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_pci.c +++ b/drivers/net/ethernet/meta/fbnic/fbnic_pci.c @@ -311,11 +311,17 @@ static int fbnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent) goto free_irqs; } + err = fbnic_fw_log_init(fbd); + if (err) + dev_warn(fbd->dev, + "Unable to initialize firmware log buffer: %d\n", + err); + err = fbnic_fw_request_mbx(fbd); if (err) { dev_err(&pdev->dev, "Firmware mailbox initialization failure\n"); - goto free_irqs; + goto free_fw_log; } /* Send the request to enable the FW logging to host. Note if this @@ -323,11 +329,7 @@ static int fbnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent) * possible the FW is just too old to support the logging and needs * to be updated. */ - err = fbnic_fw_log_init(fbd); - if (err) - dev_warn(fbd->dev, - "Unable to initialize firmware log buffer: %d\n", - err); + fbnic_fw_log_enable(fbd, true); fbnic_devlink_register(fbd); fbnic_devlink_otp_check(fbd, "error detected during probe"); @@ -374,6 +376,8 @@ init_failure_mode: * firmware updates for fixes. */ return 0; +free_fw_log: + fbnic_fw_log_free(fbd); free_irqs: fbnic_free_irqs(fbd); err_destroy_health: @@ -408,8 +412,9 @@ static void fbnic_remove(struct pci_dev *pdev) fbnic_hwmon_unregister(fbd); fbnic_dbg_fbd_exit(fbd); fbnic_devlink_unregister(fbd); - fbnic_fw_log_free(fbd); + fbnic_fw_log_disable(fbd); fbnic_fw_free_mbx(fbd); + fbnic_fw_log_free(fbd); fbnic_free_irqs(fbd); fbnic_devlink_health_destroy(fbd); -- cgit v1.2.3