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March 4, 2026 18:05
When traversing an inode’s extent tree, ext4_ext_binsearch_idx() assumes that the extent header has already been validated. However, it doesn't check header's "eh_entries" field to be non‑zero when header's depth (eh_depth) is greater than zero. If "eh_entries" value is zero, but eh_depth indicates an internal node, the macros EXT_FIRST_INDEX/EXT_LAST_INDEX return invalid pointers and the binary search reads past the allocated buffer. This leads to segv on corrupted or fuzzed ext4-images. To fix the issue check if valid entries count is not greater than max entries count.
When processing a crafted ex4-image containing malformed directory entries, it is possible for dirctory entry (de) pointer to become NULL leading to a NULL pointer dereference while reading the "name_len" field of a directory entry. To fix the issue check if de is not NULL before dereferencing it.
sigdevel
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Mar 4, 2026
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ald-rd
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When traversing an inode’s extent tree, ext4_ext_binsearch_idx() assumes that the extent header has already been validated. However, it doesn't check header's "eh_entries" field to be non‑zero when header's depth (eh_depth) is greater than zero. If "eh_entries" value is zero, but eh_depth indicates an internal node, the macros
EXT_FIRST_INDEX/EXT_LAST_INDEX return invalid pointers and the binary search reads past the allocated buffer. This leads to segv on corrupted or fuzzed ext4-images.
To fix the issue check if valid entries count is not greater than max entries count.