[lkml]   [2021]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 5.13 121/223] scsi: target: Fix NULL dereference on XCOPY completion
From: David Disseldorp <>

[ Upstream commit a47fa41381a09e5997afd762664db4f5f6657e03 ]

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.

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 <>
Signed-off-by: Sasha Levin <>
drivers/target/target_core_transport.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

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 :

- if (wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID)
+ if (!wwn || wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID)
cpu = cmd->cpuid;
cpu = wwn->cmd_compl_affinity;

 \ /
  Last update: 2021-07-26 18:34    [W:0.411 / U:0.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site