Date: Thu, 31 Mar 2022 21:31:54 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=262964 Bug ID: 262964 Summary: msdosfs: Implement BPB sanity check and replace the existing boot signature check Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: delphij@FreeBSD.org Follow up of bug 262896 , recording in the ticket so it's not forgotten. Currently we have inconsistent checks across different components, some insists 0xaa55 signature of boot sector, some are performing a subset of BPB sanity checks, etc. We should perform BPB sanity check for msdosfs related components. Some of preliminary ideas are found in https://reviews.freebsd.org/D34699 . In summary we would want to validate some simple items like: - Check if the beginning byte was an x86 JMP instruction (e9 xx xx / eb xx 90); - Bytes per sector has to be power of two and between 512 and 4096 (512, 1024, 2048 or 4096). - Sector per cluster has to be power of two and non-zero (1, 2, 4, 8, etc.) - Total sectors has to be non zero. - Reserved sectors has to be non zero. - must have at least one FAT consistently across utilities and the kernel. -- You are receiving this mail because: You are the assignee for the bug.