On 2025/5/15 09:48, Sheng Yong wrote:
From: Sheng Yong <shengyo...@xiaomi.com>
For multiple devices, both primary and extra devices should be the
same type. `erofs_init_device` has already guaranteed that if the
primary is a file-backed device, extra devices should also be
regular files.
However, if the primary is a block device while the extra device
is a file-backed device, `erofs_init_device` will get an ENOTBLK,
which is not treated as an error in `erofs_fc_get_tree`, and that
leads to an UAF:
erofs_fc_get_tree
get_tree_bdev_flags(erofs_fc_fill_super)
erofs_read_superblock
erofs_init_device // sbi->dif0 is not inited yet,
// return -ENOTBLK
deactivate_locked_super
free(sbi)
if (err is -ENOTBLK)
sbi->dif0.file = filp_open() // sbi UAF
So if -ENOTBLK is hitted in `erofs_init_device`, it means the
primary device must be a block device, and the extra device
is not a block device. The error can be converted to -EINVAL.
Fixes: fb176750266a ("erofs: add file-backed mount support")
Signed-off-by: Sheng Yong <shengyo...@xiaomi.com>
Reviewed-by: Gao Xiang <hsiang...@linux.alibaba.com>
Thanks,
Gao Xiang
