From e6965188f84a7883e6a0d3448e86b0cf29b24dfc Mon Sep 17 00:00:00 2001 From: Hamza Mahfooz Date: Wed, 5 Nov 2025 11:25:46 -0800 Subject: [PATCH 1/2] scsi: target: tcm_loop: Fix segfault in tcm_loop_tpg_address_show() If the allocation of tl_hba->sh fails in tcm_loop_driver_probe() and we attempt to dereference it in tcm_loop_tpg_address_show() we will get a segfault, see below for an example. So, check tl_hba->sh before dereferencing it. Unable to allocate struct scsi_host BUG: kernel NULL pointer dereference, address: 0000000000000194 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 8356 Comm: tokio-runtime-w Not tainted 6.6.104.2-4.azl3 #1 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 09/28/2024 RIP: 0010:tcm_loop_tpg_address_show+0x2e/0x50 [tcm_loop] ... Call Trace: configfs_read_iter+0x12d/0x1d0 [configfs] vfs_read+0x1b5/0x300 ksys_read+0x6f/0xf0 ... Cc: stable@vger.kernel.org Fixes: 2628b352c3d4 ("tcm_loop: Show address of tpg in configfs") Signed-off-by: Hamza Mahfooz Reviewed-by: Chaitanya Kulkarni Reviewed-by: Allen Pais Link: https://patch.msgid.link/1762370746-6304-1-git-send-email-hamzamahfooz@linux.microsoft.com Signed-off-by: Martin K. Petersen --- drivers/target/loopback/tcm_loop.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c index c7b7da629741..01a8e349dc4d 100644 --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -894,6 +894,9 @@ static ssize_t tcm_loop_tpg_address_show(struct config_item *item, struct tcm_loop_tpg, tl_se_tpg); struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba; + if (!tl_hba->sh) + return -ENODEV; + return snprintf(page, PAGE_SIZE, "%d:0:%d\n", tl_hba->sh->host_no, tl_tpg->tl_tpgt); } From 90449f2d1e1f020835cba5417234636937dd657e Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 13 Nov 2025 10:16:43 -0800 Subject: [PATCH 2/2] scsi: sg: Do not sleep in atomic context sg_finish_rem_req() calls blk_rq_unmap_user(). The latter function may sleep. Hence, call sg_finish_rem_req() with interrupts enabled instead of disabled. Reported-by: syzbot+c01f8e6e73f20459912e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-scsi/691560c4.a70a0220.3124cb.001a.GAE@google.com/ Cc: Hannes Reinecke Cc: stable@vger.kernel.org Fixes: 97d27b0dd015 ("scsi: sg: close race condition in sg_remove_sfp_usercontext()") Signed-off-by: Bart Van Assche Link: https://patch.msgid.link/20251113181643.1108973-1-bvanassche@acm.org Signed-off-by: Martin K. Petersen --- drivers/scsi/sg.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 4c62c597c7be..b3af9b78fa12 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -2208,9 +2208,17 @@ sg_remove_sfp_usercontext(struct work_struct *work) write_lock_irqsave(&sfp->rq_list_lock, iflags); while (!list_empty(&sfp->rq_list)) { srp = list_first_entry(&sfp->rq_list, Sg_request, entry); - sg_finish_rem_req(srp); list_del(&srp->entry); + write_unlock_irqrestore(&sfp->rq_list_lock, iflags); + + sg_finish_rem_req(srp); + /* + * sg_rq_end_io() uses srp->parentfp. Hence, only clear + * srp->parentfp after blk_mq_free_request() has been called. + */ srp->parentfp = NULL; + + write_lock_irqsave(&sfp->rq_list_lock, iflags); } write_unlock_irqrestore(&sfp->rq_list_lock, iflags);