CVSS: 4.1EPSS: 0%CPEs: 5EXPL: 0CVE-2021-47454 – powerpc/smp: do not decrement idle task preempt count in CPU offline
https://notcve.org/view.php?id=CVE-2021-47454
In the Linux kernel, the following vulnerability has been resolved: powerpc/smp: do not decrement idle task preempt count in CPU offline With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we get: BUG: scheduling while atomic: swapper/1/0/0x00000000 no locks held by swapper/1/0. CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100 Call Trace: dump_stack_lvl+0xac/0x108 __schedule_bug+0xac/0xe0 __schedule+0xcf8/0x10d0 schedule_idle+0x3c/0x70 do_idle+0x2d8/0x4a0 cpu_startup_entry+0x38/0x40 start_secondary+0x2ec/0x3a0 start_secondary_prolog+0x10/0x14 This is because powerpc's arch_cpu_idle_dead() decrements the idle task's preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc: Re-enable preemption before cpu_die()"), specifically "start_secondary() expects a preempt_count() of 0." However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled"), that justification no longer holds. The idle task isn't supposed to re-enable preemption, so remove the vestigial preempt_enable() from the CPU offline path. Tested with pseries and powernv in qemu, and pseries on PowerVM. En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: powerpc/smp: no disminuye el recuento de prioridad de tareas inactivas en la CPU fuera de línea Con PREEMPT_COUNT=y, cuando una CPU está fuera de línea y luego vuelve a estar en línea, obtenemos: ERROR: programación mientras es atómica: swapper/1/0/0x00000000 no hay bloqueos retenidos por swapper/1/0. CPU: 1 PID: 0 Comunicaciones: swapper/1 No contaminado 5.15.0-rc2+ #100 Seguimiento de llamadas: dump_stack_lvl+0xac/0x108 __schedule_bug+0xac/0xe0 __schedule+0xcf8/0x10d0 Schedule_idle+0x3c/0x70 do_idle+0x2d8/0x4a0 entrada_arriba+ 0x38/0x40 start_secondary+0x2ec/0x3a0 start_secondary_prolog+0x10/0x14 Esto se debe a que arch_cpu_idle_dead() de powerpc disminuye el recuento de apropiación de tareas inactivas, por razones explicadas en el commit a7c2bb8279d2 ("powerpc: volver a habilitar la apropiación antes de cpu_die()"), específicamente " start_secondary() espera un preempt_count() de 0." Sin embargo, desde el commit 2c669ef6979c ("powerpc/preempt: no toque el preempt_count de la tarea inactiva durante la conexión en caliente") y el commit f1a0a376ca0c ("sched/core: inicialice la tarea inactiva con la preferencia deshabilitada"), esa justificación ya no se cumple. • https://git.kernel.org/stable/c/bdf4d33e8342b90386156204e1da0cdfdb4bf146 https://git.kernel.org/stable/c/2c669ef6979c370f98d4b876e54f19613c81e075 https://git.kernel.org/stable/c/2b6148ef2bd6d8ddc76e7873114f7769b6aa25f0 https://git.kernel.org/stable/c/20a015e948b825afb47855de2efce7cae7c2608f https://git.kernel.org/stable/c/53770a411559cf7bc0906d1df319cc533d2f4f58 https://git.kernel.org/stable/c/3ea0b497a7a2fff6a4b7090310c9f52c91975934 https://git.kernel.org/stable/c/787252a10d9422f3058df9a4821f389e5326c440 https://access.redhat.com/security/cve/CVE-2021-47454 • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') •
CVSS: -EPSS: 0%CPEs: 4EXPL: 0CVE-2021-47452 – netfilter: nf_tables: skip netdev events generated on netns removal
https://notcve.org/view.php?id=CVE-2021-47452
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: skip netdev events generated on netns removal syzbot reported following (harmless) WARN: WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468 nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline] nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline] __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524 nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline] nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382 reproducer: unshare -n bash -c 'ip link add br0 type bridge; nft add table netdev t ; \ nft add chain netdev t ingress \{ type filter hook ingress device "br0" \ priority 0\; policy drop\; \}' Problem is that when netns device exit hooks create the UNREGISTER event, the .pre_exit hook for nf_tables core has already removed the base hook. Notifier attempts to do this again. The need to do base hook unregister unconditionally was needed in the past, because notifier was last stage where reg->dev dereference was safe. Now that nf_tables does the hook removal in .pre_exit, this isn't needed anymore. En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: netfilter: nf_tables: omitir eventos de netdev generados al eliminar netns syzbot informó lo siguiente (inofensivo) ADVERTENCIA: ADVERTENCIA: CPU: 1 PID: 2648 en net/netfilter/core.c:468 nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [en línea] nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [en línea] __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524 nft_netdev_event net/netfilter/nft_ filtro_cadena.c: 351 [en línea] nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382 reproductor: dejar de compartir -n bash -c 'ip link agregar puente tipo br0; nft agregar tabla netdev t; \ nft add chain netdev t ingress \{ tipo filtro gancho ingreso dispositivo "br0" \ prioridad 0\; caída de la política\; \}' El problema es que cuando los ganchos de salida del dispositivo netns crean el evento UNREGISTER, el gancho .pre_exit para nf_tables core ya ha eliminado el gancho base. Notifier intenta hacer esto nuevamente. La necesidad de cancelar el registro del enlace base incondicionalmente era necesaria en el pasado, porque el notificador era la última etapa donde la desreferencia reg->dev era segura. • https://git.kernel.org/stable/c/767d1216bff82507c945e92fe719dff2083bb2f4 https://git.kernel.org/stable/c/b110391d1e806167254d3c7ae5d637191d913175 https://git.kernel.org/stable/c/0a0e5d47670b753d3dbf88f3c77a97a30864d9bd https://git.kernel.org/stable/c/90c7c58aa2bd02c65a4c63b7dfe0b16eab12cf9f https://git.kernel.org/stable/c/68a3765c659f809dcaac20030853a054646eb739 •
CVSS: -EPSS: 0%CPEs: 3EXPL: 0CVE-2021-47451 – netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value
https://notcve.org/view.php?id=CVE-2021-47451
In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value Currently, when the rule related to IDLETIMER is added, idletimer_tg timer structure is initialized by kmalloc on executing idletimer_tg_create function. However, in this process timer->timer_type is not defined to a specific value. Thus, timer->timer_type has garbage value and it occurs kernel panic. So, this commit fixes the panic by initializing timer->timer_type using kzalloc instead of kmalloc. Test commands: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed Splat looks like: BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70 Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] dev_attr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? • https://git.kernel.org/stable/c/68983a354a655c35d3fb204489d383a2a051fda7 https://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf https://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650 https://git.kernel.org/stable/c/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e •
CVSS: -EPSS: 0%CPEs: 2EXPL: 0CVE-2021-47448 – mptcp: fix possible stall on recvmsg()
https://notcve.org/view.php?id=CVE-2021-47448
In the Linux kernel, the following vulnerability has been resolved: mptcp: fix possible stall on recvmsg() recvmsg() can enter an infinite loop if the caller provides the MSG_WAITALL, the data present in the receive queue is not sufficient to fulfill the request, and no more data is received by the peer. When the above happens, mptcp_wait_data() will always return with no wait, as the MPTCP_DATA_READY flag checked by such function is set and never cleared in such code path. Leveraging the above syzbot was able to trigger an RCU stall: rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10499 ticks this GP) idle=0af/1/0x4000000000000000 softirq=10678/10678 fqs=1 (t=10500 jiffies g=13089 q=109) rcu: rcu_preempt kthread starved for 10497 jiffies! g13089 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4955 [inline] __schedule+0x940/0x26f0 kernel/sched/core.c:6236 schedule+0xd3/0x270 kernel/sched/core.c:6315 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1955 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2128 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 8510 Comm: syz-executor827 Not tainted 5.15.0-rc2-next-20210920-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0xc8/0x180 mm/kasan/generic.c:189 Code: 38 00 74 ed 48 8d 50 08 eb 09 48 83 c0 01 48 39 d0 74 7a 80 38 00 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 <48> 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00 RSP: 0018:ffffc9000cd676c8 EFLAGS: 00000283 RAX: ffffed100e9a110e RBX: ffffed100e9a110f RCX: ffffffff88ea062a RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff888074d08870 RBP: ffffed100e9a110e R08: 0000000000000001 R09: ffff888074d08877 R10: ffffed100e9a110e R11: 0000000000000000 R12: ffff888074d08000 R13: ffff888074d08000 R14: ffff888074d08088 R15: ffff888074d08000 FS: 0000555556d8e300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 S: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000180 CR3: 0000000068909000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: instrument_atomic_read_write include/linux/instrumented.h:101 [inline] test_and_clear_bit include/asm-generic/bitops/instrumented-atomic.h:83 [inline] mptcp_release_cb+0x14a/0x210 net/mptcp/protocol.c:3016 release_sock+0xb4/0x1b0 net/core/sock.c:3204 mptcp_wait_data net/mptcp/protocol.c:1770 [inline] mptcp_recvmsg+0xfd1/0x27b0 net/mptcp/protocol.c:2080 inet6_recvmsg+0x11b/0x5e0 net/ipv6/af_inet6.c:659 sock_recvmsg_nosec net/socket.c:944 [inline] ____sys_recvmsg+0x527/0x600 net/socket.c:2626 ___sys_recvmsg+0x127/0x200 net/socket.c:2670 do_recvmmsg+0x24d/0x6d0 net/socket.c:2764 __sys_recvmmsg net/socket.c:2843 [inline] __do_sys_recvmmsg net/socket.c:2866 [inline] __se_sys_recvmmsg net/socket.c:2859 [inline] __x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2859 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fc200d2 ---truncated--- En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mptcp: corrige posible bloqueo en recvmsg() recvmsg() puede entrar en un bucle infinito si la persona que llama proporciona MSG_WAITALL, los datos presentes en la cola de recepción no son suficientes para cumplir con la solicitud y el par no recibe más datos. Cuando sucede lo anterior, mptcp_wait_data() siempre regresará sin espera, ya que el indicador MPTCP_DATA_READY verificado por dicha función se establece y nunca se borra en dicha ruta de código. Aprovechar el syzbot anterior fue capaz de desencadenar una parada de RCU: rcu: INFO: rcu_preempt parada autodetectada en la CPU rcu: 0-...! • https://git.kernel.org/stable/c/7a6a6cbc3e592e339ad23e4e8ede9a3f6160bda8 https://git.kernel.org/stable/c/1a4554e94f0deff9fc1dc5addf93fa579cc29711 https://git.kernel.org/stable/c/612f71d7328c14369924384ad2170aae2a6abd92 •
CVSS: -EPSS: 0%CPEs: 8EXPL: 0CVE-2021-47445 – drm/msm: Fix null pointer dereference on pointer edp
https://notcve.org/view.php?id=CVE-2021-47445
In the Linux kernel, the following vulnerability has been resolved: drm/msm: Fix null pointer dereference on pointer edp The initialization of pointer dev dereferences pointer edp before edp is null checked, so there is a potential null pointer deference issue. Fix this by only dereferencing edp after edp has been null checked. Addresses-Coverity: ("Dereference before null check") En el kernel de Linux, se resolvió la siguiente vulnerabilidad: drm/msm: corrige la desreferencia del puntero nulo en el puntero edp. La inicialización del puntero dev desreferencias del puntero edp antes de edp se marca como nula, por lo que existe un posible problema de deferencia del puntero nulo. Solucione este problema eliminando la referencia a edp únicamente después de que se haya marcado como nulo. Direcciones-Cobertura: ("Desreferencia antes de verificación nula") • https://git.kernel.org/stable/c/ab5b0107ccf3821a6837b0f2819270d6fa0b278f https://git.kernel.org/stable/c/f175b9a83e5c252d7c74acddc792840016caae0a https://git.kernel.org/stable/c/bacac7d26849c8e903ceb7466d9ce8dc3c2797eb https://git.kernel.org/stable/c/0cd063aa0a09822cc1620fc59a67fe2f9f6338ac https://git.kernel.org/stable/c/7f642b93710b6b1119bdff90be01e6b5a2a5d669 https://git.kernel.org/stable/c/f302be08e3de94db8863a0b2958b2bb3e8e998e6 https://git.kernel.org/stable/c/91a340768b012f5b910a203a805b97a345b3db37 https://git.kernel.org/stable/c/46c8ddede0273d1d132beefa9de8b8203 •