CVE-2021-47117

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ext4: corrigió el error en ext4_es_cache_extent ya que ext4_split_extent_at falló. Obtuvimos el seguimiento de bug_on cuando ejecutamos fsstress con la inyección de error de IO: [130747.323114] ERROR del kernel en fs/ext4/extents_status.c:762. [130747.323117] Error interno: Vaya - ERROR: 0 [#1] SMP ...... [130747.334329] Rastreo de llamadas: [130747.334553] ext4_es_cache_extent+0x150/0x168 [ext4] [130747.334975] ext4_cache_extents+0x 64/0xe8 [ext4] [130747.335368] text4_find_extent+0x300/0x330 [ext4] [130747.335759] text4_ext_map_blocks+0x74/0x1178 [ext4] [130747.336179] text4_map_blocks+0x2f4/0x5f0 [ext4] [130747.336567] ext4_mpage_readpages+0x4a8/0x7a8 [ext4] [130747.336995] ext4_readpage+0x54 /0x100 [ext4] [130747.337359] generic_file_buffered_read+0x410/0xae8 [130747.337767] generic_file_read_iter+0x114/0x190 [130747.338152] ext4_file_read_iter+0x5c/0x140 [ext4] [13 0747.338556] __vfs_read+0x11c/0x188 [130747.338851] vfs_read+0x94/0x150 [130747.339110 ] ksys_read+0x74/0xf0 La modificación de este parche se realiza según la sugerencia de Jan Kara en: https://patchwork.ozlabs.org/project/linux-ext4/patch/20210428085158.3728201-1-yebin10@huawei.com/ "Ya veo. Ahora Entiendo su parche. Honestamente, viendo lo frágil que es intentar arreglar el árbol de extensión después de que la división falló en el medio, probablemente iría aún más lejos y me aseguraría de arreglar el árbol correctamente en el caso de ENOSPC y EDQUOT (esos son fácilmente activables por el usuario). ). Cualquier otra cosa indica un problema de hardware o corrupción de fs, por lo que prefiero dejar el árbol de extensiones como está y no intentar arreglarlo (lo que también significa que no crearemos extensiones superpuestas)".

In the Linux kernel, the following vulnerability has been resolved: ext4: fix bug on in ext4_es_cache_extent as ext4_split_extent_at failed We got follow bug_on when run fsstress with injecting IO fault: [130747.323114] kernel BUG at fs/ext4/extents_status.c:762! [130747.323117] Internal error: Oops - BUG: 0 [#1] SMP ...... [130747.334329] Call trace: [130747.334553] ext4_es_cache_extent+0x150/0x168 [ext4] [130747.334975] ext4_cache_extents+0x64/0xe8 [ext4] [130747.335368] ext4_find_extent+0x300/0x330 [ext4] [130747.335759] ext4_ext_map_blocks+0x74/0x1178 [ext4] [130747.336179] ext4_map_blocks+0x2f4/0x5f0 [ext4] [130747.336567] ext4_mpage_readpages+0x4a8/0x7a8 [ext4] [130747.336995] ext4_readpage+0x54/0x100 [ext4] [130747.337359] generic_file_buffered_read+0x410/0xae8 [130747.337767] generic_file_read_iter+0x114/0x190 [130747.338152] ext4_file_read_iter+0x5c/0x140 [ext4] [130747.338556] __vfs_read+0x11c/0x188 [130747.338851] vfs_read+0x94/0x150 [130747.339110] ksys_read+0x74/0xf0 This patch's modification is according to Jan Kara's suggestion in: https://patchwork.ozlabs.org/project/linux-ext4/patch/20210428085158.3728201-1-yebin10@huawei.com/ "I see. Now I understand your patch. Honestly, seeing how fragile is trying to fix extent tree after split has failed in the middle, I would probably go even further and make sure we fix the tree properly in case of ENOSPC and EDQUOT (those are easily user triggerable). Anything else indicates a HW problem or fs corruption so I'd rather leave the extent tree as is and don't try to fix it (which also means we will not create overlapping extents)."