Title: kernel de Linux
Description: En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: corrige la carrera de datos en btrfs_use_block_rsv() al acceder a la reserva de bloque En btrfs_use_block_rsv() leemos el tamaño de una reserva de bloque sin bloquear su spinlock, lo que hace que KCSAN se queje porque el tamaño de una reserva de bloque siempre se actualiza mientras se mantiene su bloqueo de giro. El informe de KCSAN es el siguiente: [653.313148] ERROR: KCSAN: data-race en btrfs_update_delayed_refs_rsv [btrfs] / btrfs_use_block_rsv [btrfs] [653.314755] leído en 0x000000017f5871b8 de 8 bytes por tarea 7519 en 0: [653.314779] btrfs_use_block_rsv+0xe4 /0x2f8 [btrfs] [653.315606] btrfs_alloc_tree_block+0xdc/0x998 [btrfs] [653.316421] btrfs_force_cow_block+0x220/0xe38 [btrfs] [653.317242] 8 [btrfs] [653.318060] btrfs_search_slot+0xda2/0x19b8 [btrfs] [ 653.318879] btrfs_del_csums+0x1dc/0x798 [btrfs] [653.319702] __btrfs_free_extent.isra.0+0xc24/0x2028 [btrfs] [653.320538] __btrfs_run_delayed_refs+0xd3c/0x 2390 [btrfs] [653.321340] btrfs_run_delayed_refs+0xae/0x290 [btrfs] [653.322140] flush_space+0x5e4/0x718 [btrfs] [653.322958] btrfs_preempt_reclaim_metadata_space+0x102/0x2f8 [btrfs] [653.323781] Process_one_work+0x3b6/0x838 [653.323800] trabajador_thread+0x75e/0xb1 0 [653.323817] kthread+0x21a/0x230 [653.323836] __ret_from_fork+0x6c/ 0xb8 [653.323855] ret_from_fork+0xa/0x30 [653.323887] escribe en 0x000000017f5871b8 de 8 bytes por tarea 576 en la CPU 3: [653.323906] [btrfs] [653.324699] btrfs_add_delayed_data_ref+0x468/0x6d8 [btrfs] [653.325494] btrfs_free_extent+0x76/0x120 [btrfs] [653.326280] __btrfs_mod_ref+0x6a8/0x6b8 [btrfs] [653.327064] btrfs_dec_ref+0x50/0x70 [btrfs] [653.327849] 236/0xa50 [btrfs] [653.328633] walk_up_tree+0x21c/0x448 [ btrfs] [653.329418] btrfs_drop_snapshot+0x802/0x1328 [btrfs] [653.330205] btrfs_clean_one_deleted_snapshot+0x184/0x238 [btrfs] [653.330995] clean_kthread+0x2b0/0x2f0 [ btrfs] [653.331781] kthread+0x21a/0x230 [653.331800] __ret_from_fork+0x6c/ 0xb8 [653.331818] ret_from_fork+0xa/0x30 Entonces agregue un ayudante para obtener el tamaño de una reserva de bloque mientras mantiene el bloqueo. Se utiliza la lectura del campo mientras se mantiene presionado el candado en lugar de usar la anotación data_race() para evitar el desgarro de la carga.

OR
     
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 from (excluding) 6.7.11
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 from (excluding) 6.6.23
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5 from (excluding) 6.1.83
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (excluding) 5.4.273

NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NIST CWE-667

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix data race at btrfs_use_block_rsv() when accessing block reserve

At btrfs_use_block_rsv() we read the size of a block reserve without
locking its spinlock, which makes KCSAN complain because the size of a
block reserve is always updated while holding its spinlock. The report
from KCSAN is the following:

  [653.313148] BUG: KCSAN: data-race in btrfs_update_delayed_refs_rsv [btrfs] / btrfs_use_block_rsv [btrfs]

  [653.314755] read to 0x000000017f5871b8 of 8 bytes by task 7519 on cpu 0:
  [653.314779]  btrfs_use_block_rsv+0xe4/0x2f8 [btrfs]
  [653.315606]  btrfs_alloc_tree_block+0xdc/0x998 [btrfs]
  [653.316421]  btrfs_force_cow_block+0x220/0xe38 [btrfs]
  [653.317242]  btrfs_cow_block+0x1ac/0x568 [btrfs]
  [653.318060]  btrfs_search_slot+0xda2/0x19b8 [btrfs]
  [653.318879]  btrfs_del_csums+0x1dc/0x798 [btrfs]
  [653.319702]  __btrfs_free_extent.isra.0+0xc24/0x2028 [btrfs]
  [653.320538]  __btrfs_run_delayed_refs+0xd3c/0x2390 [btrfs]
  [653.321340]  btrfs_run_delayed_refs+0xae/0x290 [btrfs]
  [653.322140]  flush_space+0x5e4/0x718 [btrfs]
  [653.322958]  btrfs_preempt_reclaim_metadata_space+0x102/0x2f8 [btrfs]
  [653.323781]  process_one_work+0x3b6/0x838
  [653.323800]  worker_thread+0x75e/0xb10
  [653.323817]  kthread+0x21a/0x230
  [653.323836]  __ret_from_fork+0x6c/0xb8
  [653.323855]  ret_from_fork+0xa/0x30

  [653.323887] write to 0x000000017f5871b8 of 8 bytes by task 576 on cpu 3:
  [653.323906]  btrfs_update_delayed_refs_rsv+0x1a4/0x250 [btrfs]
  [653.324699]  btrfs_add_delayed_data_ref+0x468/0x6d8 [btrfs]
  [653.325494]  btrfs_free_extent+0x76/0x120 [btrfs]
  [653.326280]  __btrfs_mod_ref+0x6a8/0x6b8 [btrfs]
  [653.327064]  btrfs_dec_ref+0x50/0x70 [btrfs]
  [653.327849]  walk_up_proc+0x236/0xa50 [btrfs]
  [653.328633]  walk_up_tree+0x21c/0x448 [btrfs]
  [653.329418]  btrfs_drop_snapshot+0x802/0x1328 [btrfs]
  [653.330205]  btrfs_clean_one_deleted_snapshot+0x184/0x238 [btrfs]
  [653.330995]  cleaner_kthread+0x2b0/0x2f0 [btrfs]
  [653.331781]  kthread+0x21a/0x230
  [653.331800]  __ret_from_fork+0x6c/0xb8
  [653.331818]  ret_from_fork+0xa/0x30

So add a helper to get the size of a block reserve while holding the lock.
Reading the field while holding the lock instead of using the data_race()
annotation is used in order to prevent load tearing.

Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

kernel.org https://git.kernel.org/stable/c/2daa2a8e895e6dc2395f8628c011bcf1e019040d

kernel.org https://git.kernel.org/stable/c/7e9422d35d574b646269ca46010a835ca074b310

kernel.org https://git.kernel.org/stable/c/ab1be3f1aa7799f99155488c28eacaef65eb68fb

kernel.org https://git.kernel.org/stable/c/c7bb26b847e5b97814f522686068c5628e2b3646

kernel.org https://git.kernel.org/stable/c/f6d4d29a12655b42a13cec038c2902bb7efc50ed