CVE-2026-97903

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> exit: hold a reference to thread_pid across proc_flush_pid<br /> <br /> Commit 0a36bad01731 ("release_task: kill the no longer needed<br /> get/put_pid(thread_pid)") removed the reference around proc_flush_pid().<br /> It assumed that free_pids(post.pids) at the end of release_task() would<br /> keep thread_pid alive until then.<br /> <br /> That assumption is wrong. __change_pid() only records a detached PID in<br /> post.pids when pid_has_task() is false for every PIDTYPE. If another task<br /> still uses the exiting task&amp;#39;s PID as its process group or session ID,<br /> __unhash_process() removes the exiting task&amp;#39;s PIDTYPE_PID link but leaves<br /> the PID out of post.pids. release_task() therefore holds no reference to<br /> it after dropping tasklist_lock.<br /> <br /> The other task can then remove the remaining PIDTYPE links. Its<br /> free_pids() call schedules delayed_put_pid(), and the RCU callback can free<br /> the PID before the first release_task() reaches proc_flush_pid().<br /> <br /> An unprivileged reproducer races wait4(-1) against setsid() to trigger this<br /> ordering. Three of three fresh v7.2 KASAN boots reported:<br /> <br /> BUG: KASAN: slab-use-after-free in<br /> proc_invalidate_siblings_dcache+0x3e2/0x3f0<br /> Read of size 8 by task h7_pid_reaper/1921<br /> <br /> Call Trace:<br /> proc_invalidate_siblings_dcache<br /> release_task<br /> wait_consider_task<br /> __do_wait<br /> do_wait<br /> kernel_wait4<br /> <br /> Freed by task 0:<br /> kmem_cache_free<br /> put_pid<br /> delayed_put_pid<br /> rcu_core<br /> <br /> Last potentially related work creation:<br /> __call_rcu_common<br /> free_pids<br /> ksys_setsid<br /> <br /> KASAN identified a 144-byte object from the pid cache and located the bad<br /> read 80 bytes into the freed object, matching pid-&gt;inodes. With an<br /> explicit reference, three of three fresh boots completed without a KASAN<br /> report. The concurrent RCU callback dropped its reference while<br /> proc_flush_pid() was protected, and the balancing put_pid() performed the<br /> final free afterward.<br /> <br /> Take a reference before __unhash_process() clears p-&gt;thread_pid and release<br /> it after proc_flush_pid() completes.<br /> <br /> A tested source reproducer is available privately on request. No<br /> controlled read or write, information leak, or privilege escalation is<br /> claimed. The mainline patch applies directly to v6.19.y and newer;<br /> v6.16.y through v6.18.y need a context-adjusted backport.