"value":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: aovid use-after-free in ext4_ext_insert_extent()\n\nAs Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is\nreallocated in ext4_ext_create_new_leaf(), we'll use the stale path and\ncause UAF. Below is a sample trace with dummy values:\n\next4_ext_insert_extent\n path = *ppath = 2000\n ext4_ext_create_new_leaf(ppath)\n ext4_find_extent(ppath)\n path = *ppath = 2000\n if (depth > path[0].p_maxdepth)\n kfree(path = 2000);\n *ppath = path = NULL;\n path = kcalloc() = 3000\n *ppath = 3000;\n return path;\n /* here path is still 2000, UAF! */\n eh = path[depth].p_hdr\n\n==================================================================\nBUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330\nRead of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179\nCPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866\nCall Trace:\n <TASK>\n ext4_ext_insert_extent+0x26d4/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n[...]\n\nAllocated by task 179:\n ext4_find_extent+0x81c/0x1f70\n ext4_ext_map_blocks+0x146/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n\nFreed by task 179:\n kfree+0xcb/0x240\n ext4_find_extent+0x7c0/0x1f70\n ext4_ext_insert_extent+0xa26/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n==================================================================\n\nSo use *ppath to update the path to avoid the above problem."
"value":"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: evitar use-after-free en ext4_ext_insert_extent() Como mencion\u00f3 Ojaswin en Link, en ext4_ext_insert_extent(), si la ruta se reasigna en ext4_ext_create_new_leaf(), usaremos la ruta obsoleta y causaremos UAF. A continuaci\u00f3n, se muestra un seguimiento de muestra con valores ficticios: ext4_ext_insert_extent path = *ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = *ppath = 2000 if (depth > path[0].p_maxdepth) kfree(path = 2000); *ppath = path = NULL; path = kcalloc() = 3000 *ppath = 3000; return path; /* aqu\u00ed la ruta sigue siendo 2000, UAF! */ eh = path[depth].p_hdr ===================================================================== ERROR: KASAN: slab-use-after-free en ext4_ext_insert_extent+0x26d4/0x3330 Lectura de tama\u00f1o 8 en la direcci\u00f3n ffff8881027bf7d0 por la tarea kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 No contaminado 6.11.0-rc2-dirty #866 Seguimiento de llamadas: ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...] Asignado por la tarea 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] Liberado por la tarea 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...]================================================================== As\u00ed que use *ppath para actualizar el path para evitar el problema de arriba"