NuytsTech Security

CVE-2025-40241

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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.

More information : https://git.kernel.org/stable/c/00d8fe0b72f4ca0a983abced36aad2160038c421

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