From 2f3897ea9496058fa0a43e126bf886aae8ea9751 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 commit 057085e522f8bf94c2e691a5b76880f68060f8ba upstream. 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 Signed-off-by: Nicholas Bellinger [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- 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 edfd69a25884..0c37d70a4f57 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -518,7 +518,7 @@ struct se_cmd { sense_reason_t (*execute_cmd)(struct se_cmd *); sense_reason_t (*execute_rw)(struct se_cmd *, struct scatterlist *, u32, enum dma_data_direction); - sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool); + sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool, int *); unsigned char *t_task_cdb; unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE]; -- cgit v1.2.3