🛡️ CVE-2025-40241 — kernel

erofs: fix crafted invalid cases for encoded extents

In the Linux kernel, the following vulnerability has been resolved:

erofs: fix crafted invalid cases for encoded extents

Robert recently reported two corrupted images that can cause system

crashes, which are related to the new encoded extents introduced

in Linux 6.15:

• The first one [1] has plen != 0 (e.g. plen == 0x2000000) but

(plen & Z_EROFS_EXTENT_PLEN_MASK) == 0. It is used to represent

special extents such as sparse extents (!EROFS_MAP_MAPPED), but

previously only plen == 0 was handled;

• The second one [2] has pa 0xffffffffffdcffed and plen 0xb4000,

then "cur [0xfffffffffffff000] += bvec.bv_len [0x1000]" in

"} while ((cur += bvec.bv_len) < end);" wraps around, causing an

out-of-bound access of pcl->compressed_bvecs[] in

z_erofs_submit_queue(). EROFS only supports 48-bit physical block

addresses (up to 1EiB for 4k blocks), so add a sanity check to

enforce this.