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CVE-2026-89525

udf: reject VAT indexes equal to the entry count PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: udf: reject VAT indexes equal to the entry count UDF 1.50 virtual partition mapping uses the VAT as an array of physical block mappings. s_num_entries stores the number of entries in that array, not the highest valid index. The valid VAT indexes are therefore below s_num_entries. udf_get_pblock_virt15() currently rejects only indexes greater than s_num_entries. A crafted image can request index s_num_entries, pass the bounds check, and make the kernel read one entry past the allocated VAT table. Change the check to reject block >= s_num_entries, so the count is handled as an exclusive upper bound. A crafted UDF image reproduced this on origin/master commit 0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53 with a KASAN slab-out-of-bounds report in udf_get_pblock_virt15(). Trail of Bits has a reproducer that triggers kernel panic demonstrating the bug, and can share it if needed.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before f64e01a90326bb85a3cc8aa0199931dc2f15b589; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 8a8c1c42a34349a0626d910abbad5a29136446b7; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 19f36c6453cd88fe6d60ef36ab1f1cad8ddf4ce4; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before b77b83f5529a26d084d64ece98abd6f0cc86e053; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 9193368408d792cec2057628d87862140fb1ce1c; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before b95c33a4e743874f1b0a45bf2aaa4da553552bd1; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 1bd7947f1463c21edafa256d0fbec5b99215e2b6; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before cac0cb07f29ccfb373fd4a36c81e908ef3ce608c
Linux / Linuxaffected 2.6.12; unaffected 0 before 2.6.12; unaffected 5.10.270 through 5.10.*; unaffected 5.15.221 through 5.15.*; unaffected 6.1.188 through 6.1.*; unaffected 6.6.157 through 6.6.*; unaffected 6.12.109 through 6.12.*; unaffected 6.18.50 through 6.18.*; unaffected 7.2.4 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References