UBUNTU-CVE-2026-89490: Medium severity ubuntu/linux vulnerability

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix readdir position truncation on 32-bit kernels In ocfs2dirforeachblkel(), the directory cookie position is rebuilt with ctx->pos = (ctx->pos & ~(sb->sblocksize - 1)) | offset; ctx->pos is lofft (signed 64-bit), while sb->sblocksize is unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask ~(sb->sblocksize - 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 ocfs2dirforeachblkel(), 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 lofft so the mask is 64-bit before the AND: ctx->pos = (ctx->pos & ~((lofft)sb->sblocksize - 1)) | offset; 64-bit kernels are unaffected.