In the Linux kernel, the following vulnerability has been resolved:
ntfs: fix off-by-one in mapping pairs decoding bounds checks
In ntfs_mapping_pairs_decompress(), attr_end points one byte past the end of the attribute record:
attr_end = (u8 *)attr + le32_to_cpu(attr->length);
The two bounds checks validating that mapping pair data bytes fit within the attribute use strict greater-than (>), which allows a one-byte out-of-bounds read when the data extends exactly to attr_end:
b = *buf & 0xf; if (b) { if (unlikely(buf + b > attr_end)) // off-by-one goto io_error; for (deltaxcn = (s8)buf[b–]; b; b–) deltaxcn = (deltaxcn « 8) + buf[b]; }
When buf + b == attr_end, the check evaluates to false and buf[b] reads one byte past the valid attribute boundary. The same pattern appears in the LCN delta bytes check.
Fix both checks to use >= so that buf[b] at exactly attr_end is correctly rejected as out of bounds.