From a47fa41381a09e5997afd762664db4f5f6657e03 Mon Sep 17 00:00:00 2001 From: David Disseldorp Date: Wed, 21 Jul 2021 00:55:22 +0200 Subject: scsi: target: Fix NULL dereference on XCOPY completion CPU affinity control added with commit 39ae3edda325 ("scsi: target: core: Make completion affinity configurable") makes target_complete_cmd() queue work on a CPU based on se_tpg->se_tpg_wwn->cmd_compl_affinity state. LIO's EXTENDED COPY worker is a special case in that read/write cmds are dispatched using the global xcopy_pt_tpg, which carries a NULL se_tpg_wwn pointer following initialization in target_xcopy_setup_pt(). The NULL xcopy_pt_tpg->se_tpg_wwn pointer is dereferenced on completion of any EXTENDED COPY initiated read/write cmds. E.g using the libiscsi SCSI.ExtendedCopy.Simple test: BUG: kernel NULL pointer dereference, address: 00000000000001a8 RIP: 0010:target_complete_cmd+0x9d/0x130 [target_core_mod] Call Trace: fd_execute_rw+0x148/0x42a [target_core_file] ? __dynamic_pr_debug+0xa7/0xe0 ? target_check_reservation+0x5b/0x940 [target_core_mod] __target_execute_cmd+0x1e/0x90 [target_core_mod] transport_generic_new_cmd+0x17c/0x330 [target_core_mod] target_xcopy_issue_pt_cmd+0x9/0x60 [target_core_mod] target_xcopy_read_source.isra.7+0x10b/0x1b0 [target_core_mod] ? target_check_fua+0x40/0x40 [target_core_mod] ? transport_complete_task_attr+0x130/0x130 [target_core_mod] target_xcopy_do_work+0x61f/0xc00 [target_core_mod] This fix makes target_complete_cmd() queue work on se_cmd->cpuid if se_tpg_wwn is NULL. Link: https://lore.kernel.org/r/20210720225522.26291-1-ddiss@suse.de Fixes: 39ae3edda325 ("scsi: target: core: Make completion affinity configurable") Cc: Lee Duncan Cc: Mike Christie Reviewed-by: Mike Christie Signed-off-by: David Disseldorp Signed-off-by: Martin K. Petersen --- drivers/target/target_core_transport.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/target') diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 7e35eddd9eb7..26ceabe34de5 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -886,7 +886,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status) INIT_WORK(&cmd->work, success ? target_complete_ok_work : target_complete_failure_work); - if (wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID) + if (!wwn || wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID) cpu = cmd->cpuid; else cpu = wwn->cmd_compl_affinity; -- cgit v1.2.3