Commit 84dc6037 authored by Maurizio Lombardi's avatar Maurizio Lombardi Committed by Martin K. Petersen
Browse files

scsi: target: iscsi: Fix use-after-free in iscsit_dec_session_usage_count() 



In iscsit_dec_session_usage_count(), the function calls complete() while
holding the sess->session_usage_lock. Similar to the connection usage count
logic, the waiter signaled by complete() (e.g., in the session release
path) may wake up and free the iscsit_session structure immediately.

This creates a race condition where the current thread may attempt to
execute spin_unlock_bh() on a session structure that has already been
deallocated, resulting in a KASAN slab-use-after-free.

To resolve this, release the session_usage_lock before calling complete()
to ensure all dereferences of the sess pointer are finished before the
waiter is allowed to proceed with deallocation.

Signed-off-by: default avatarMaurizio Lombardi <mlombard@redhat.com>
Reported-by: default avatarZhaojuan Guo <zguo@redhat.com>
Reviewed-by: default avatarMike Christie <michael.christie@oracle.com>
Link: https://patch.msgid.link/20260112165352.138606-3-mlombard@redhat.com


Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 9411a89e

drivers/target/iscsi/iscsi_target_util.c

+4 −1
Original line number Diff line number Diff line
@@ -741,8 +741,11 @@ void iscsit_dec_session_usage_count(struct iscsit_session *sess) 
	spin_lock_bh(&sess->session_usage_lock);

	sess->session_usage_count--;



	if (!sess->session_usage_count && sess->session_waiting_on_uc)

	if (!sess->session_usage_count && sess->session_waiting_on_uc) {

		spin_unlock_bh(&sess->session_usage_lock);

		complete(&sess->session_waiting_on_uc_comp);

		return;

	}



	spin_unlock_bh(&sess->session_usage_lock);

}