NVD description
In the Linux kernel, the following vulnerability has been resolved:
udf: validate free block extents against the partition length
udf_free_blocks() checks the logical block number and count against the
partition length, but drops the extent offset from that final bound. A
crafted extent can pass the guard while logicalBlockNum + offset + count
points past the partition, which later indexes past the space bitmap
array.
A single ftruncate(2) on a file backed by such an extent reliably
panics the kernel. This is a local availability issue. On desktop
systems where UDisks/polkit allows the active user to mount removable
UDF media without CAP_SYS_ADMIN, an unprivileged local user can supply
the crafted filesystem and trigger the panic by truncating a writable
file on it. Systems that require root or CAP_SYS_ADMIN to mount the
image have a higher prerequisite.
No confidentiality or integrity impact is claimed: the reproduced
primitive is an out-of-bounds read of a bitmap pointer slot followed by
a kernel panic.
Use the already computed logicalBlockNum + offset + count value for the
partition length check. Also make load_block_bitmap() reject an
out-of-range block group before indexing s_block_bitmap[], so corrupted
callers cannot walk past the flexible array.
