CVE-2026-93191
2026-09-17
17h18 +00:00
17h18 +00:00
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Deskripsi CVE
In the Linux kernel, the following vulnerability has been resolved:
smack: fix incorrect task context in smack_msg_queue_msgrcv
The smack_msg_queue_msgrcv() function incorrectly checks
the permissions of the 'current' task instead of the
'target' task.
In the msgsnd() syscall path, if a receiver is already waiting,
the pipelined_send() optimization is used to push the message
directly to the receiver task:
ipc/msg.c`pipelined_send():
` smp_store_release(&msr->r_msg, msg)
In this case, the 'sender' (current) task performs the check
on behalf of the 'receiver' task (msr->r_tsk, passed as the
'target' parameter):
ipc/msg.c`pipelined_send():
` security_msg_queue_msgrcv(,, target := msr->r_tsk,,)
However, smack_msg_queue_msgrcv() ignores the 'target' and
checks 'current':
smack_msg_queue_msgrcv(…)
` smk_curacc_msq(isp, MAY_READWRITE); // current task
'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement,
but 'target' (the receiver task) might NOT;
as a result, an unauthorized receiver gets the message,
violating MAC policy.
Test:
1) create a sysv message queue with label “foo”
2) echo "bar foo r" >/smack/load2
3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task.
The task is waiting for the messages ...
4) msgsnd() from a "foo"-labeled task:
"bar"-labeled task gets the message.
This patch fixes the issue by checking permission on the
'target' task instead of 'current'.
(2008-02-04, Casey Schaufler)
