CVE-2024-27031

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: NFS: corrige el bloqueo de matriz x de nfs_netfs_issue_read() para interrupción de escritura regresiva. El bucle dentro de nfs_netfs_issue_read() actualmente no deshabilita las interrupciones mientras se itera a través de páginas en la matriz x para enviarlas a lectura NFS. Sin embargo, esto no es seguro ya que después de tomar xa_lock, otra página en el mapeo podría procesarse para reescritura dentro de una interrupción, y puede ocurrir un punto muerto. La solución es simple y limpia si usamos xa_for_each_range(), que maneja la iteración con RCU mientras reduce la complejidad del código. El problema se reproduce fácilmente con la siguiente prueba: mount -o vers=3,fsc 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file1.bin bs=4096 count= 1 echo 3 > /proc/sys/vm/drop_caches dd if=/mnt/nfs/file1.bin of=/dev/null umount /mnt/nfs En la consola con un kernel habilitado para lockdep aparecerá un mensaje similar al siguiente ser visto: ================================ ADVERTENCIA: estado de bloqueo inconsistente 6.7.0-lockdbg+ #10 No contaminado - ------------------------------- Uso inconsistente de {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W}. test5/1708 [HC0[0]:SC0[0]:HE1:SE1] toma: ffff888127baa598 (&xa->xa_lock#4){+.?.}-{3:3}, en: nfs_netfs_issue_read+0x1b2/0x4b0 [ nfs] El estado {IN-SOFTIRQ-W} se registró en: lock_acquire+0x144/0x380 _raw_spin_lock_irqsave+0x4e/0xa0 __folio_end_writeback+0x17e/0x5c0 folio_end_writeback+0x93/0x1b0 iomap_finish_ioend+0xeb/0x6a0 blk_update_request+ 0x204/0x7f0 blk_mq_end_request+0x30/0x1c0 blk_complete_reqs +0x7e/0xa0 __do_softirq+0x113/0x544 __irq_exit_rcu+0xfe/0x120 irq_exit_rcu+0xe/0x20 sysvec_call_function_single+0x6f/0x90 asm_sysvec_call_function_single+0x1a/0x20 +0xf/0x20 default_idle+0x9/0x20 default_idle_call+0x67/0xa0 do_idle+0x2b5/0x300 cpu_startup_entry +0x34/0x40 start_secondary+0x19d/0x1c0 second_startup_64_no_verify+0x18f/0x19b sello de evento irq: 176891 hardirqs habilitado por última vez en (176891): [] _raw_spin_unlock_irqrestore+0x44/0x60 hardirqs deshabilitado por última vez en ( 176890): [] _raw_spin_lock_irqsave+0x79/0xa0 softirqs habilitado por última vez en (176646): [] __irq_exit_rcu+0xfe/0x120 softirqs deshabilitado por última vez en (176633): [] __irq_exit_rcu+0xfe/0x120 Otra información que podría ayudarnos a depurar esto: Posible escenario de bloqueo inseguro: CPU0 ---- lock(&xa->xa_lock#4); bloqueo(&xa->xa_lock#4); *** DEADLOCK *** 2 bloqueos mantenidos por test5/1708: #0: ffff888127baa498 (&sb->s_type->i_mutex_key#22){++++}-{4:4}, en: nfs_start_io_read+0x28/0x90 [nfs] #1: ffff888127baa650 (mapping.invalidate_lock#3){.+.+}-{4:4}, en: page_cache_ra_unbounded+0xa4/0x280 seguimiento de pila: CPU: 6 PID: 1708 Comm: test5 Kdump: cargado No tainted 6.7.0-lockdbg+ Nombre del hardware: PC estándar QEMU (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 01/04/2014 Seguimiento de llamadas: dump_stack_lvl+0x5b/0x90 mark_lock+0xb3f/0xd20 __lock_acquire+0x77b/ 0x3360 _raw_spin_lock+0x34/0x80 nfs_netfs_issue_read+0x1b2/0x4b0 [nfs] netfs_begin_read+0x77f/0x980 [netfs] nfs_netfs_readahead+0x45/0x60 [nfs_readahead+0x323/0x5 a0 [nfs] read_pages+0xf3/0x5c0 page_cache_ra_unbounded+0x1c8/0x280 filemap_get_pages+ 0x38c/0xae0 filemap_read+0x206/0x5e0 nfs_file_read+0xb7/0x140 [nfs] vfs_read+0x2a9/0x460 ksys_read+0xb7/0x140

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix nfs_netfs_issue_read() xarray locking for writeback interrupt The loop inside nfs_netfs_issue_read() currently does not disable interrupts while iterating through pages in the xarray to submit for NFS read. This is not safe though since after taking xa_lock, another page in the mapping could be processed for writeback inside an interrupt, and deadlock can occur. The fix is simple and clean if we use xa_for_each_range(), which handles the iteration with RCU while reducing code complexity. The problem is easily reproduced with the following test: mount -o vers=3,fsc 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file1.bin bs=4096 count=1 echo 3 > /proc/sys/vm/drop_caches dd if=/mnt/nfs/file1.bin of=/dev/null umount /mnt/nfs On the console with a lockdep-enabled kernel a message similar to the following will be seen: ================================ WARNING: inconsistent lock state 6.7.0-lockdbg+ #10 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. test5/1708 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff888127baa598 (&xa->xa_lock#4){+.?.}-{3:3}, at: nfs_netfs_issue_read+0x1b2/0x4b0 [nfs] {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x144/0x380 _raw_spin_lock_irqsave+0x4e/0xa0 __folio_end_writeback+0x17e/0x5c0 folio_end_writeback+0x93/0x1b0 iomap_finish_ioend+0xeb/0x6a0 blk_update_request+0x204/0x7f0 blk_mq_end_request+0x30/0x1c0 blk_complete_reqs+0x7e/0xa0 __do_softirq+0x113/0x544 __irq_exit_rcu+0xfe/0x120 irq_exit_rcu+0xe/0x20 sysvec_call_function_single+0x6f/0x90 asm_sysvec_call_function_single+0x1a/0x20 pv_native_safe_halt+0xf/0x20 default_idle+0x9/0x20 default_idle_call+0x67/0xa0 do_idle+0x2b5/0x300 cpu_startup_entry+0x34/0x40 start_secondary+0x19d/0x1c0 secondary_startup_64_no_verify+0x18f/0x19b irq event stamp: 176891 hardirqs last enabled at (176891): [<ffffffffa67a0be4>] _raw_spin_unlock_irqrestore+0x44/0x60 hardirqs last disabled at (176890): [<ffffffffa67a0899>] _raw_spin_lock_irqsave+0x79/0xa0 softirqs last enabled at (176646): [<ffffffffa515d91e>] __irq_exit_rcu+0xfe/0x120 softirqs last disabled at (176633): [<ffffffffa515d91e>] __irq_exit_rcu+0xfe/0x120 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&xa->xa_lock#4); <Interrupt> lock(&xa->xa_lock#4); *** DEADLOCK *** 2 locks held by test5/1708: #0: ffff888127baa498 (&sb->s_type->i_mutex_key#22){++++}-{4:4}, at: nfs_start_io_read+0x28/0x90 [nfs] #1: ffff888127baa650 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: page_cache_ra_unbounded+0xa4/0x280 stack backtrace: CPU: 6 PID: 1708 Comm: test5 Kdump: loaded Not tainted 6.7.0-lockdbg+ Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/2014 Call Trace: dump_stack_lvl+0x5b/0x90 mark_lock+0xb3f/0xd20 __lock_acquire+0x77b/0x3360 _raw_spin_lock+0x34/0x80 nfs_netfs_issue_read+0x1b2/0x4b0 [nfs] netfs_begin_read+0x77f/0x980 [netfs] nfs_netfs_readahead+0x45/0x60 [nfs] nfs_readahead+0x323/0x5a0 [nfs] read_pages+0xf3/0x5c0 page_cache_ra_unbounded+0x1c8/0x280 filemap_get_pages+0x38c/0xae0 filemap_read+0x206/0x5e0 nfs_file_read+0xb7/0x140 [nfs] vfs_read+0x2a9/0x460 ksys_read+0xb7/0x140

Ziming Zhang discovered that the DRM driver for VMware Virtual GPU did not properly handle certain error conditions, leading to a NULL pointer dereference. A local attacker could possibly trigger this vulnerability to cause a denial of service. Zheng Wang discovered that the Broadcom FullMAC WLAN driver in the Linux kernel contained a race condition during device removal, leading to a use- after-free vulnerability. A physically proximate attacker could possibly use this to cause a denial of service.