Re: [LTP] cve: reproducer for cve-2026-64600

[linuxtestproject.agent@gmail.com]

Hi Andrea,

On Fri, 31 Jul 2026, Andrea Cervesato wrote:
> cve: reproducer for cve-2026-64600

> 	while (!stop_pressure) {
> 		SAFE_PWRITE(1, fd, wbuf, blksize, 0);
> 		SAFE_FTRUNCATE(fd, 0);
> 		SAFE_FSYNC(fd);
> 	}

Could the write be synced before the truncate? The truncate can discard the
dirty page and delayed allocation before writeback, so fsync() only persists
the empty file. This also differs from the documented
write/fdatasync/truncate sequence and may leave the XFS log without the
allocation pressure needed to widen the vulnerable window, causing false
passes on affected kernels.

Verdict - Needs revision

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