From: Leon Romanovsky <leonro@nvidia.com>
Date: Wed, 22 Jul 2026 06:30:10 +0000 (+0300)
Subject: scsi: target: Clear cmd_cnt when initial counter enrollment fails
X-Git-Tag: v7.2-rc6~7^2~2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a8ddfd2425bbbafadae8700d63ed8a61a4109878;p=thirdparty%2Fkernel%2Fstable.git

scsi: target: Clear cmd_cnt when initial counter enrollment fails

When target_get_sess_cmd() fails during session shutdown because
percpu_ref_tryget_live() returns false, the command keeps the
se_cmd->cmd_cnt pointer that __target_init_cmd() assigned earlier
without owning a reference. Final release through
target_release_cmd_kref() then issues an unmatched percpu_ref_put().

Commit 8e288be8606a ("scsi: target: Pass in cmd counter to use during
cmd setup") moved the cmd_cnt assignment ahead of the reference
acquisition.  Clear se_cmd->cmd_cnt whenever the initial
target_get_sess_cmd() fails in target_init_cmd() and
target_submit_tmr(), so release performs exactly one matching put per
acquired reference.

Fixes: 8e288be8606a ("scsi: target: Pass in cmd counter to use during cmd setup")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Link: https://patch.msgid.link/20260722-reference-count-underflow-in-target-v1-1-63ab664f12fd@nvidia.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
---

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index fad03a15c969..dcfe94594916 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1734,6 +1734,7 @@ int target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
 		    u32 data_length, int task_attr, int data_dir, int flags)
 {
 	struct se_portal_group *se_tpg;
+	int ret;
 
 	se_tpg = se_sess->se_tpg;
 	BUG_ON(!se_tpg);
@@ -1763,7 +1764,11 @@ int target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
 	 * necessary for fabrics using TARGET_SCF_ACK_KREF that expect a second
 	 * kref_put() to happen during fabric packet acknowledgement.
 	 */
-	return target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
+	ret = target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
+	if (ret)
+		se_cmd->cmd_cnt = NULL;
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(target_init_cmd);
 
@@ -2039,8 +2044,10 @@ int target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
 	 * allocation failure.
 	 */
 	ret = core_tmr_alloc_req(se_cmd, fabric_tmr_ptr, tm_type, gfp);
-	if (ret < 0)
+	if (ret < 0) {
+		se_cmd->cmd_cnt = NULL;
 		return -ENOMEM;
+	}
 
 	if (tm_type == TMR_ABORT_TASK)
 		se_cmd->se_tmr_req->ref_task_tag = tag;
@@ -2048,6 +2055,7 @@ int target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
 	/* See target_submit_cmd for commentary */
 	ret = target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
 	if (ret) {
+		se_cmd->cmd_cnt = NULL;
 		core_tmr_release_req(se_cmd->se_tmr_req);
 		return ret;
 	}