Description

In the Linux kernel, the following vulnerability has been resolved: ubi: Fix use-after-free when volume resizing failed There is an use-after-free problem reported by KASAN: ================================================================== BUG: KASAN: use-after-free in ubi_eba_copy_table+0x11f/0x1c0 [ubi] Read of size 8 at addr ffff888101eec008 by task ubirsvol/4735 CPU: 2 PID: 4735 Comm: ubirsvol Not tainted 6.1.0-rc1-00003-g84fa3304a7fc-dirty #14 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x34/0x44 print_report+0x171/0x472 kasan_report+0xad/0x130 ubi_eba_copy_table+0x11f/0x1c0 [ubi] ubi_resize_volume+0x4f9/0xbc0 [ubi] ubi_cdev_ioctl+0x701/0x1850 [ubi] __x64_sys_ioctl+0x11d/0x170 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> When ubi_change_vtbl_record() returns an error in ubi_resize_volume(), "new_eba_tbl" will be freed on error handing path, but it is holded by "vol->eba_tbl" in ubi_eba_replace_table(). It means that the liftcycle of "vol->eba_tbl" and "vol" are different, so when resizing volume in next time, it causing an use-after-free fault. Fix it by not freeing "new_eba_tbl" after it replaced in ubi_eba_replace_table(), while will be freed in next volume resizing.

References 8

• git.kernel.org https://git.kernel.org/stable/c/35f8d4064e54c18424db2997059d4c0b1d13d093
• git.kernel.org https://git.kernel.org/stable/c/3d6378f7056ac7350338f941001162a8f660853c
• git.kernel.org https://git.kernel.org/stable/c/53818746e549e61841428892a8d94344494be797
• git.kernel.org https://git.kernel.org/stable/c/9af31d6ec1a4be4caab2550096c6bd2ba8fba472
• git.kernel.org https://git.kernel.org/stable/c/9c8be1f165baee53b5a36ea0b3c9281d403a1d0b
• git.kernel.org https://git.kernel.org/stable/c/b0c951742348d216f094d16ed4f70ae73db881c0
• git.kernel.org https://git.kernel.org/stable/c/bf795ebbb9995e2fe7945de71177f01c2f1215dc
• git.kernel.org https://git.kernel.org/stable/c/bf9875aa7f7d624a8c084425b14bf7e5907ebc30

Remediation