CVE-2026-89492ocfs2: validate directory-index entry counts when reading metadata

Official description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: validate directory-index entry counts when reading metadata ocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() check the ECC and signature of an indexed-directory block before it reaches higher-level callers, but neither validator bounds the ocfs2_dx_entry_list counts against the capacity of the block that holds them. ocfs2_dx_dir_search() then walks for (i = 0; i < le16_to_cpu(entry_list->de_num_used); i++) dx_entry = &entry_list->de_entries[i]; over de_num_used entries with no bounds check. entry_list is either dx_leaf->dl_list (from ocfs2_read_dx_leaf) or, for an inline root, dx_root->dr_entries. A crafted on-disk image can set de_num_used (and de_count, which is the __counted_by_le() bound of de_entries) to 0xffff and make the walk read far past the end of the 4KB metadata block, giving a slab out-of-bounds read reachable from any path lookup, stat() or open() on an indexed directory once the image is mounted. Commit 775c17386a6f ("ocfs2: validate dx_root extent list fields during block read") already bounds dr_list for the non-inline dx_root, but left the inline dr_entries path and the dx_leaf dl_list unchecked. Add the same read-time validation for both entry lists: de_count must equal the capacity of the block (ocfs2_dx_entries_per_leaf()/per_root()) and de_num_used must not exceed de_count, rejecting corrupted metadata with -EFSCORRUPTED before ocfs2_dx_dir_search() can walk an out-of-range entry array. de_count is always written as exactly the block capacity when a leaf or inline root is formatted, so the equality check does not reject any valid image. Found by 0sec automated security-research tooling (https://0sec.ai).

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3f28574dd59672ac47f3110c9a8ead703ec021c0
• https://git.kernel.org/stable/c/3497aa757788de5d904f41814f1df0b292a8be09
• https://git.kernel.org/stable/c/47b8152ed7709f7ef30b398fb0bfe4b452dd0495
• https://git.kernel.org/stable/c/aad3129b8e915d0ff492bb7517d825d8490cfdd9
• https://git.kernel.org/stable/c/5e661f55ca8568471fce558effe81cca112f5cb2
• https://git.kernel.org/stable/c/fcfcba8fe17dbf2c8805690b8cc25e32d81249a4
• https://git.kernel.org/stable/c/b8a5c0c32df2c5b685ceef76ac77e37c7e1dc3ed
• https://git.kernel.org/stable/c/bc70726ddad53c7e9a9a85915bf2415b0d4f42f9