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ubi: Fix use-after-free when volume resizing failed

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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.

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Li Zetao 2022-10-21 18:21:56 +08:00 committed by Richard Weinberger
parent e874dcde1c
commit 9af31d6ec1
1 changed files with 3 additions and 1 deletions
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4
drivers/mtd/ubi/vmt.c
View File

@ -464,7 +464,7 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
for (i = 0; i < -pebs; i++) { for (i = 0; i < -pebs; i++) {
err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i); err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
if (err) if (err)
goto out_acc; goto out_free;
} }
spin_lock(&ubi->volumes_lock); spin_lock(&ubi->volumes_lock);
ubi->rsvd_pebs += pebs; ubi->rsvd_pebs += pebs;
@ -512,6 +512,8 @@ out_acc:
ubi->avail_pebs += pebs; ubi->avail_pebs += pebs;
spin_unlock(&ubi->volumes_lock); spin_unlock(&ubi->volumes_lock);
} }
return err;
out_free: out_free:
kfree(new_eba_tbl); kfree(new_eba_tbl);
return err; return err;