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 <[email protected]>
---
drivers/mtd/ubi/vmt.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 8fcc0bdf0635..74637575346e 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -464,7 +464,7 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
for (i = 0; i < -pebs; i++) {
err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
if (err)
- goto out_acc;
+ goto out_free;
}
spin_lock(&ubi->volumes_lock);
ubi->rsvd_pebs += pebs;
@@ -512,6 +512,8 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
ubi->avail_pebs += pebs;
spin_unlock(&ubi->volumes_lock);
}
+ return err;
+
out_free:
kfree(new_eba_tbl);
return err;
--
2.31.1
?? 2022/10/21 18:21, Li Zetao ะด??:
> 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 <[email protected]>
> ---
> drivers/mtd/ubi/vmt.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
> index 8fcc0bdf0635..74637575346e 100644
> --- a/drivers/mtd/ubi/vmt.c
> +++ b/drivers/mtd/ubi/vmt.c
> @@ -464,7 +464,7 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
> for (i = 0; i < -pebs; i++) {
> err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
> if (err)
> - goto out_acc;
> + goto out_free;
> }
> spin_lock(&ubi->volumes_lock);
> ubi->rsvd_pebs += pebs;
> @@ -512,6 +512,8 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
> ubi->avail_pebs += pebs;
> spin_unlock(&ubi->volumes_lock);
> }
> + return err;
> +
> out_free:
> kfree(new_eba_tbl);
> return err;
Reviewed-by: Zhihao Cheng <[email protected]>