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df86e81f0a
When mounting ubifs e.g. through command 'ubifsmount' one global static
superblock 'ubifs_sb' is used _and_ the requested volume is opened (like
in Linux). The pointer returned by 'ubifs_open_volume()' is stored in
that superblock struct and freed later on cmd 'ubifsumount' or another
call to 'ubifsmount' with a different volume, through ubifs_umount() and
ubi_close_volume().
In ubifs_ls(), ubifs_exists(), ubifs_size(), and ubifs_read() the volume
was opened again, which is technically no problem with regard to
refcounting, but here the still valid pointer in sb was overwritten,
leading to a memory leak. Even worse, when using one of those
functions and calling ubifsumount later, ubi_close_volume() was called
again but now on an already freed pointer, leading to a double free.
This actually crashed with different invalid memory accesses on a board
using the old distro boot and a rather long script handling RAUC
updates.
Example:
> ubi part UBI
> ubifsmount ubi0:boot
> test -e ubi ubi0:boot /boot.scr.uimg
> ubifsumount
The ubifs specific commands 'ubifsls' and 'ubifsload' check for a
mounted volume by themselves, for the generic fs variants 'ls', 'load',
(and 'size', and 'test -e') this is covered by special ubifs handling in
fs_set_blk_dev() and deeper down blk_get_device_part_str() then. So for
ubifs_ls(), ubifs_exists(), ubifs_size(), and ubifs_read() we can be
sure the volume is opened and the necessary struct pointer in sb is
valid, so it is not needed to open volume again.
Fixes:
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||
|---|---|---|
| .. | ||
| btrfs | ||
| cbfs | ||
| cramfs | ||
| erofs | ||
| ext4 | ||
| fat | ||
| jffs2 | ||
| sandbox | ||
| squashfs | ||
| ubifs | ||
| yaffs2 | ||
| zfs | ||
| fs.c | ||
| fs_internal.c | ||
| Kconfig | ||
| Makefile | ||
| semihostingfs.c | ||