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CVE-2026-89786

ext4: fix out-of-bounds read in ext4_read_inline_dir()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, and 1 more
None on Exploit-DB, Metasploit or GitHub

Summary

The vulnerability affects the Linux kernel's ext4 filesystem driver, specifically its handling of directories stored inline within an inode. A crafted filesystem or directory structure can cause the kernel to read memory beyond the end of an allocated buffer, which could lead to a crash or information disclosure when listing directory contents.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix out-of-bounds read in ext4_read_inline_dir() ext4_read_inline_dir() can read a dirent header past the end of its inline buffer, triggering a slab-out-of-bounds read during getdents64(): BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry Read of size 2 at addr ffff88800f3dd23c by task exploit/148 ... __ext4_check_dir_entry ext4_read_inline_dir iterate_dir The dirent payload lives in a buffer of exactly inline_size bytes: dir_buf = kmalloc(inline_size, GFP_NOFS); but iteration runs in a position space extra_offset bytes larger (extra_size = extra_offset + inline_size) so the synthetic "." and ".." land at their block-dir offsets. A dirent is formed at "dir_buf + pos - extra_offset", yet the ext4_check_dir_entry() length argument uses the larger extra_size. A position whose dirent header would extend past extra_size is therefore accepted, and the rescan loop's rec_len probe and ext4_check_dir_entry() dereference de->rec_len before the entry is rejected. Reject a position whose minimum-size dirent header would not fit within extra_size before forming de, in both the rescan and main loops, and pass inline_size rather than extra_size to ext4_check_dir_entry() so the length check matches the physical buffer.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in d1e7c186555ad65554fd2f2b02f5a539aa35ae48; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in 5fd20d4e50dd6e460b3ea8e4396f8553d4526f8f; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in 1a1dea633b724a1c042dbcdb1fed27f410916688; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in b060861f662d4826dc700a1c3584243bb3474cfe; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in 6702c7da86d8cdb88d0fc57166286e115ffeb8c0; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in 36bf17bb90cdf7a623499b624b05acde4d2feef5; From c4d8b0235aa98f8c26bf94d308be3fdd24154572 · fixed in 9333cc809f0a89e001b814155a6cb8903a6274df

  • Linux Linux

    3.10

  • KernelLinux

    From 3.10.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6

References 7

git.kernel.org