CVE-2024-26923

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: af_unix: corrige la ejecución del recolector de basura contra connect() El recolector de basura no tiene en cuenta el riesgo de que el embrión quede en cola durante la recolección de basura. Si dicho embrión tiene un par que porta SCM_RIGHTS, dos pases consecutivos de scan_children() pueden ver un conjunto diferente de niños. Lo que lleva a un recuento en vuelo elevado incorrectamente y luego a un puntero colgante dentro de gc_inflight_list. los sockets son AF_UNIX/SOCK_STREAM S es un socket no conectado L es un socket de escucha en vuelo vinculado a addr, no en fdtable El fd de V se pasará a través de sendmsg(), se aumenta el recuento en vuelo connect(S, addr) sendmsg(S, [ V]); cerrar(V) __unix_gc() ---------- ------------------------- -- --------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 en vuelo=0 NS = unix_peer(S ) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V se convirtió en vuelo // V recuento=2 en vuelo=1 close(V) // V recuento=1 en vuelo=1 // Condición candidata de GC cumplida para u en gc_inflight_list: if (total_refs == inflight_refs) agregue u a gc_candidates // gc_candidates={L, V} para u en gc_candidates: scan_children(u, dec_inflight) // el embrión (skb1) aún no era // accesible desde L , por lo que V's // en vuelo permanece sin cambios __skb_queue_tail(L, skb1) unix_state_unlock(L) para u en gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) Si hay un socket de escucha candidato a GC, bloquear/desbloquear su estado. Esto hace que GC espere hasta el final de cualquier conexión () en curso a ese socket. Después de girar la cerradura, un embrión posiblemente cargado de SCM ya está en cola. Y si viene otro embrión, no es posible que porte SCM_RIGHTS. En este punto, unix_inflight() no puede ocurrir porque unix_gc_lock ya está en uso. El gráfico a bordo no se ve afectado.

A flaw was found in the Linux kernel, where the management of inter-process communication uses AF_UNIX sockets. The issue arises from a race condition where a partially initialized socket with specific permissions carrying SCM_RIGHTS is improperly handled during garbage collection. This situation leads to an incorrect count of active sockets, potentially causing resources to remain unaccounted for and never released.

In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list. sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- ----------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0 NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V became in-flight // V count=2 inflight=1 close(V) // V count=1 inflight=1 // GC candidate condition met for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates // gc_candidates={L, V} for u in gc_candidates: scan_children(u, dec_inflight) // embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) If there is a GC-candidate listening socket, lock/unlock its state. This makes GC wait until the end of any ongoing connect() to that socket. After flipping the lock, a possibly SCM-laden embryo is already enqueued. And if there is another embryo coming, it can not possibly carry SCM_RIGHTS. At this point, unix_inflight() can not happen because unix_gc_lock is already taken. Inflight graph remains unaffected.

黄思聪 discovered that the NFC Controller Interface implementation in the Linux kernel did not properly handle certain memory allocation failure conditions, leading to a null pointer dereference vulnerability. A local attacker could use this to cause a denial of service. It was discovered that a race condition existed in the Bluetooth subsystem in the Linux kernel when modifying certain settings values through debugfs. A privileged local attacker could use this to cause a denial of service.