xfs: fix log recovery buffer allocation for the legacy h_size fixup

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: xfs: fix log recovery buffer allocation for the legacy h_size fixup Commit a70f9fe52daa ("xfs: detect and handle invalid iclog size set by mkfs") added a fixup for incorrect h_size values used for the initial umount record in old xfsprogs versions. Later commit 0c771b99d6c9 ("xfs: clean up calculation of LR header blocks") cleaned up the log reover buffer calculation, but stoped using the fixed up h_size value to size the log recovery buffer, which can lead to an out of bounds access when the incorrect h_size does not come from the old mkfs tool, but a fuzzer. Fix this by open coding xlog_logrec_hblks and taking the fixed h_size into account for this calculation.

References

• https://git.kernel.org/stable/c/f754591b17d0ee91c2b45fe9509d0cdc420527cb
• https://git.kernel.org/stable/c/57835c0e7152e36b03875dd6c56dfeed685c1b1f
• https://git.kernel.org/stable/c/c2389c074973aa94e34992e7f66dac0de37595b5
• https://git.kernel.org/stable/c/45cf976008ddef4a9c9a30310c9b4fb2a9a6602a