CVE-2021-46959

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: spi: corrige el Use-After-Free con devm_spi_alloc_* No podemos confiar en el contenido de la lista devres durante spi_unregister_controller(), ya que la lista ya está eliminada en ese momento. Realizamos devres_find() para devm_spi_release_controller. Esto hace que los dispositivos registrados con devm_spi_alloc_{master,slave}() se identifiquen erróneamente como dispositivos heredados, no administrados por devm y sus contadores de referencia disminuyan por debajo de 0. ------------[ cortar aquí ] ------------ ADVERTENCIA: CPU: 1 PID: 660 en lib/refcount.c:28 refcount_warn_saturate+0x108/0x174 [] (refcount_warn_saturate) de [] (kobject_put+ 0x90/0x98) [] (kobject_put) de [] (put_device+0x20/0x24) r4:b6700140 [] (put_device) de [] (devm_spi_release_controller+0x3c/0x40 ) [ ] (devm_spi_release_controller) de [] (release_nodes+0x84/0xc4) r5:b6700180 r4:b6700100 [] (release_nodes) de [] (devres_release_all+0x5c/0x6 0) r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10 [] (devres_release_all) de [] (__device_release_driver+0x144/0x1ec) r5:b117ad94 r4:b163dc10 [] (__device_release_driver) de [< b044f70c>] (device_driver_detach+0x84/0xa0) r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10 [] (device_driver_detach) de [ ] (unbind_store+0xe4/0xf8) en su lugar , determine el estado de asignación devm como un indicador en el controlador que se garantiza que será estable durante la limpieza.

In the Linux kernel, the following vulnerability has been resolved: spi: Fix use-after-free with devm_spi_alloc_* We can't rely on the contents of the devres list during spi_unregister_controller(), as the list is already torn down at the time we perform devres_find() for devm_spi_release_controller. This causes devices registered with devm_spi_alloc_{master,slave}() to be mistakenly identified as legacy, non-devm managed devices and have their reference counters decremented below 0. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174 [<b0396f04>] (refcount_warn_saturate) from [<b03c56a4>] (kobject_put+0x90/0x98) [<b03c5614>] (kobject_put) from [<b0447b4c>] (put_device+0x20/0x24) r4:b6700140 [<b0447b2c>] (put_device) from [<b07515e8>] (devm_spi_release_controller+0x3c/0x40) [<b07515ac>] (devm_spi_release_controller) from [<b045343c>] (release_nodes+0x84/0xc4) r5:b6700180 r4:b6700100 [<b04533b8>] (release_nodes) from [<b0454160>] (devres_release_all+0x5c/0x60) r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10 [<b0454104>] (devres_release_all) from [<b044e41c>] (__device_release_driver+0x144/0x1ec) r5:b117ad94 r4:b163dc10 [<b044e2d8>] (__device_release_driver) from [<b044f70c>] (device_driver_detach+0x84/0xa0) r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10 [<b044f688>] (device_driver_detach) from [<b044d274>] (unbind_store+0xe4/0xf8) Instead, determine the devm allocation state as a flag on the controller which is guaranteed to be stable during cleanup.