CVE-2024-26696

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: nilfs2: corrige un bloqueo en nilfs_lookup_dirty_data_buffers() Syzbot informó un problema de bloqueo en migrar_pages_batch() llamado por mbind() y nilfs_lookup_dirty_data_buffers() llamado en el escritor de registros de nilfs2. Mientras migrar_pages_batch() bloquea una publicación y espera a que se complete la reescritura, el subproceso del escritor de registros que debería completar la reescritura recoge la publicación que se está reescribiendo en nilfs_lookup_dirty_data_buffers() que solicita la creación de registros posteriores y estaba intentando bloquear la fol. Provocando así un punto muerto. En primer lugar, es inesperado que los folios/páginas en medio de la reescritura se actualicen y se ensucien. Nilfs2 agrega una suma de verificación para verificar la validez del registro que se está escribiendo y la usa para la recuperación en el montaje, de modo que se suprimen los cambios de datos durante la reescritura. Dado que esto no funciona, un cierre incorrecto podría provocar que falle la recuperación. La investigación reveló que la causa principal es que la espera para que se complete la reescritura en nilfs_page_mkwrite() es condicional, y si el dispositivo de respaldo no requiere escrituras estables, los datos se pueden modificar sin esperar. Solucione estos problemas haciendo que nilfs_page_mkwrite() espere a que finalice la reescritura independientemente del requisito de escritura estable del dispositivo de respaldo.

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix hang in nilfs_lookup_dirty_data_buffers() Syzbot reported a hang issue in migrate_pages_batch() called by mbind() and nilfs_lookup_dirty_data_buffers() called in the log writer of nilfs2. While migrate_pages_batch() locks a folio and waits for the writeback to complete, the log writer thread that should bring the writeback to completion picks up the folio being written back in nilfs_lookup_dirty_data_buffers() that it calls for subsequent log creation and was trying to lock the folio. Thus causing a deadlock. In the first place, it is unexpected that folios/pages in the middle of writeback will be updated and become dirty. Nilfs2 adds a checksum to verify the validity of the log being written and uses it for recovery at mount, so data changes during writeback are suppressed. Since this is broken, an unclean shutdown could potentially cause recovery to fail. Investigation revealed that the root cause is that the wait for writeback completion in nilfs_page_mkwrite() is conditional, and if the backing device does not require stable writes, data may be modified without waiting. Fix these issues by making nilfs_page_mkwrite() wait for writeback to finish regardless of the stable write requirement of the backing device.

It was discovered that the Open vSwitch implementation in the Linux kernel could overflow its stack during recursive action operations under certain conditions. A local attacker could use this to cause a denial of service. Sander Wiebing, Alvise de Faveri Tron, Herbert Bos, and Cristiano Giuffrida discovered that the Linux kernel mitigations for the initial Branch History Injection vulnerability were insufficient for Intel processors. A local attacker could potentially use this to expose sensitive information.