CVE-2026-64322

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

udf: validate sparing table length as an entry count, not a byte count

udf_load_sparable_map() accepts a sparing table when

sizeof(*st) + le16_to_cpu(st->reallocationTableLen) > sb->s_blocksize

is false, i.e. it treats reallocationTableLen as a number of BYTES that must fit in the block. But the table is walked as an array of 8-byte sparingEntry elements:

for (i = 0; i < le16_to_cpu(st->reallocationTableLen); i++) {
	struct sparingEntry *entry = &st->mapEntry[i];
	... entry->origLocation ...
}

in udf_get_pblock_spar15() and udf_relocate_blocks(). A reallocationTableLen of N therefore passes the check whenever sizeof(*st) + N <= blocksize, yet the consumers index sizeof(*st) + N * sizeof(struct sparingEntry) bytes – up to ~8x the block. On a crafted UDF image this is an out-of-bounds read in udf_get_pblock_spar15(); udf_relocate_blocks() additionally feeds the same length to udf_update_tag(), whose crc_itu_t() reads far past the block, and its memmove() through st->mapEntry[] is an out-of-bounds write.

Validate reallocationTableLen as the entry count it is, with struct_size().

Affected Software

References

• https://git.kernel.org/stable/c/04f4599a9efb90992d072a814960edf0cd62805d
• https://git.kernel.org/stable/c/0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9
• https://git.kernel.org/stable/c/2a219acb2ce674d99bbd1b7b35ed8c384dac7200
• https://git.kernel.org/stable/c/2d726135099313958f8975532a2e15322ff150ce
• https://git.kernel.org/stable/c/3ec997bd5508e9b25210b5bbec89031629cdb093
• https://git.kernel.org/stable/c/7285276aa50d2839afb5957ffd491ad282dc8f72
• https://git.kernel.org/stable/c/7f7774b9da0ef17b87bfa238cf966ad0b3376150
• https://git.kernel.org/stable/c/eeb0f3e193f8e523d03e4c9e084f6b4875f50e8e