The Linux kernel netfs subsystem performed write streaming to cache dirty data and avoid unnecessary reads. Write streaming was disabled if the file descriptor was opened with O_RDWR, among other conditions, to ensure data consistency during reads. However, this disabling was unnecessary because netfs now fills in data gaps on read, and the previous logic did not work correctly if a separate file descriptor was open for reading. The vulnerability was fixed by removing the O_RDWR check, allowing streaming writes even when reads might occur. This fix resolves issues observed in generic/522 xfstest.

The vulnerability could cause incorrect handling of write streaming caching in netfs, potentially leading to data consistency issues or functional problems when a file descriptor is opened with O_RDWR. The CVSS score of 7.3 (high) indicates a significant impact on confidentiality, integrity, and availability with low attack complexity and low privileges required. However, no known exploits in the wild have been reported.

A fix has been implemented in the Linux kernel to remove the disabling of write streaming for O_RDWR file descriptors. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the vendor or Linux kernel advisories for the exact fixed versions and update accordingly.