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fs: ubifs: Fix memleak and double free in u-boot wrapper functions

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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: 9eefe2a2b3 ("UBIFS: Implement read-only UBIFS support in U-Boot")
Fixes: 29cc5bcadf ("ubifs: Add functions for generic fs use")
Signed-off-by: Alexander Dahl <ada@thorsis.com>
This commit is contained in:
Alexander Dahl
2024-07-03 12:12:55 +02:00
committed by Heiko Schocher
parent 7bd2559cb3
commit df86e81f0a
1 changed files with 0 additions and 12 deletions
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12
fs/ubifs/ubifs.c
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@@ -614,7 +614,6 @@ int ubifs_set_blk_dev(struct blk_desc *rbdd, struct disk_partition *info)
int ubifs_ls(const char *filename)
{
struct ubifs_info *c = ubifs_sb->s_fs_info;
struct file *file;
struct dentry *dentry;
struct inode *dir;
@@ -622,7 +621,6 @@ int ubifs_ls(const char *filename)
unsigned long inum;
int ret = 0;
c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
inum = ubifs_findfile(ubifs_sb, (char *)filename);
if (!inum) {
ret = -1;
@@ -656,31 +654,24 @@ out_mem:
free(dir);
out:
ubi_close_volume(c->ubi);
return ret;
}
int ubifs_exists(const char *filename)
{
struct ubifs_info *c = ubifs_sb->s_fs_info;
unsigned long inum;
c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
inum = ubifs_findfile(ubifs_sb, (char *)filename);
ubi_close_volume(c->ubi);
return inum != 0;
}
int ubifs_size(const char *filename, loff_t *size)
{
struct ubifs_info *c = ubifs_sb->s_fs_info;
unsigned long inum;
struct inode *inode;
int err = 0;
c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
inum = ubifs_findfile(ubifs_sb, (char *)filename);
if (!inum) {
err = -1;
@@ -698,7 +689,6 @@ int ubifs_size(const char *filename, loff_t *size)
ubifs_iput(inode);
out:
ubi_close_volume(c->ubi);
return err;
}
@@ -893,7 +883,6 @@ int ubifs_read(const char *filename, void *buf, loff_t offset,
return -1;
}
c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
/* ubifs_findfile will resolve symlinks, so we know that we get
* the real file here */
inum = ubifs_findfile(ubifs_sb, (char *)filename);
@@ -957,7 +946,6 @@ put_inode:
ubifs_iput(inode);
out:
ubi_close_volume(c->ubi);
return err;
}