ocfs2: fix readdir position truncation on 32-bit kernels

Summary

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix readdir position truncation on 32-bit kernels In ocfs2_dir_foreach_blk_el(), the directory cookie position is rebuilt with ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset; `ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask ~(sb->s_blocksize - 1) is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB block size). In the AND expression with the 64-bit `ctx->pos`, that unsigned operand is zero-extended to 64 bits per the usual arithmetic conversions, yielding 0x00000000fffff000. The high 32 bits of `ctx->pos` are silently cleared, even though directory size is allowed to exceed 4 GiB. When readdir() crosses the 4 GiB boundary on a 32-bit kernel the position is reset back into the first 4 GiB block, making the re-validation path re-enumerate already-returned dirents indefinitely. This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken for all non-inline directories, so a directory large enough to cross 4 GiB reaches it. This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix bitwise operation having different size") fixed in exfat, and the fix mirrors the equivalent ext4 fix in this series. Cast the operand to loff_t so the mask is 64-bit before the AND: ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset; 64-bit kernels are unaffected.

Timeline

1. Sep 11, 2026, 7:43 PM UTCCVE published
2. Oct 19, 2026, 8:47 AM UTCRecord last updated

Affected versions

• Linux Linux

  From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in c28dc3407937aa8f225942538cd585c9b28ea65a; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in 94569154ba49f5f85645d2019c8e206213d8404e; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in 1ae7029823ae4c91664cb32eec7fb8dd5e1a337a; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in f9dd5cad8d09110ddff2db1fe756aae93c7552ff; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in 1001fb3b69a11eaa0dc7c7428f6edfa48b88997a; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in c0c165487a2ea5a37ddcdab4259157b7a527129c; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in b53e2b271eeb6040c2a4a78230c570dc41cdcfa4; From ccd979bdbce9fba8412beb3f1de68a9d0171b12c · fixed in a63308ab426f3a3c7e33b02c150ea59054620261

• Linux Linux

  2.6.16

• KernelLinux

  From 2.6.16 · fixed in 5.10.270; From 5.11.0 · 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 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8