From 057085e522f8bf94c2e691a5b76880f68060f8ba Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Thu, 5 Nov 2015 23:37:59 -0800 Subject: target: Fix race for SCF_COMPARE_AND_WRITE_POST checking This patch addresses a race + use after free where the first stage of COMPARE_AND_WRITE in compare_and_write_callback() is rescheduled after the backend sends the secondary WRITE, resulting in second stage compare_and_write_post() callback completing in target_complete_ok_work() before the first can return. Because current code depends on checking se_cmd->se_cmd_flags after return from se_cmd->transport_complete_callback(), this results in first stage having SCF_COMPARE_AND_WRITE_POST set, which incorrectly falls through into second stage CAW processing code, eventually triggering a NULL pointer dereference due to use after free. To address this bug, pass in a new *post_ret parameter into se_cmd->transport_complete_callback(), and depend upon this value instead of ->se_cmd_flags to determine when to return or fall through into ->queue_status() code for CAW. Cc: Sagi Grimberg Cc: # v3.12+ Signed-off-by: Nicholas Bellinger --- include/target/target_core_base.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/target') diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 0a2c74008e53..aabf0aca0171 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -474,7 +474,7 @@ struct se_cmd { struct completion cmd_wait_comp; const struct target_core_fabric_ops *se_tfo; sense_reason_t (*execute_cmd)(struct se_cmd *); - sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool); + sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool, int *); void *protocol_data; unsigned char *t_task_cdb; -- cgit v1.2.3