Unbuffered Write Stream Error Handling in Linux Kernel

CVE-2025-39723

What is CVE-2025-39723?

A vulnerability in the Linux kernel affects unbuffered write stream error handling. When all subrequests in an unbuffered write fail, the stream's transfer value remains incorrectly set to LONG_MAX. This mismanagement can lead to erroneous return values from the write_iter function, which subsequently causes system malfunctions, including NULL pointer dereferences in critical functions like iter_file_splice_write. Proper validation flags have now been implemented to ensure accurate handling of these error states, thereby enhancing system stability.

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