From b71cb088b2e3427924a470fc43e7aedb8a40d2e3 Mon Sep 17 00:00:00 2001 From: Guixin Liu Date: Fri, 24 Apr 2026 09:39:23 +0800 Subject: scsi: target: tcm_loop: Fix NULL ptr dereference The TCM_LOOP LUN creation process calls device_register() to create the device, which in turn invokes tcm_loop_driver_probe() registered with the TCM_LOOP bus to create and register the scsi_host. However, if the scsi_host memory allocation fails or scsi_add_host() fails, the device_register() process still returns success. Subsequently, when the user binds the LUN to a specific backend device, it accesses the NULL or freed scsi_host. Crash Call Trace: RIP: 0010:scsi_is_host_device+0x7/0x20 scsi_alloc_target+0x32/0x2c0 __scsi_add_device+0x41/0xf0 scsi_add_device+0xd/0x30 tcm_loop_port_link+0x25/0x50 [tcm_loop] target_fabric_port_link+0x9c/0xb0 [target_core_mod] ... This issue is fixed by: 1. Setting the tcm_loop_hba's scsi_host to NULL, if scsi_add_host() fails. 2. Checking the tcm_loop_hba's scsi_host after device_register(). 3. Checking the tcm_loop_hba's scsi_host in tcm_loop_driver_remove(). Fixes: 3703b2c5d041 ("[SCSI] tcm_loop: Add multi-fabric Linux/SCSI LLD fabric module") Signed-off-by: Guixin Liu Reviewed-by: Mike Christie Link: https://patch.msgid.link/20260424013923.25998-1-kanie@linux.alibaba.com Signed-off-by: Martin K. Petersen --- drivers/target/loopback/tcm_loop.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'drivers/target/loopback') diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c index a25fd826b542..110297345751 100644 --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -393,6 +393,7 @@ static int tcm_loop_driver_probe(struct device *dev) if (error) { pr_err("%s: scsi_add_host failed\n", __func__); scsi_host_put(sh); + tl_hba->sh = NULL; return -ENODEV; } return 0; @@ -406,8 +407,10 @@ static void tcm_loop_driver_remove(struct device *dev) tl_hba = to_tcm_loop_hba(dev); sh = tl_hba->sh; - scsi_remove_host(sh); - scsi_host_put(sh); + if (sh) { + scsi_remove_host(sh); + scsi_host_put(sh); + } } static void tcm_loop_release_adapter(struct device *dev) @@ -436,6 +439,11 @@ static int tcm_loop_setup_hba_bus(struct tcm_loop_hba *tl_hba, int tcm_loop_host return -ENODEV; } + if (!tl_hba->sh) { + device_unregister(&tl_hba->dev); + return -ENODEV; + } + return 0; } -- cgit v1.2.3