Date: Fri, 16 Jun 2023 15:04:07 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 272018] pci_read_vpd() does not always load VPD even when valid VPD exists because of state machine bug Message-ID: <bug-272018-227-U8htX5FK6b@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-272018-227@https.bugs.freebsd.org/bugzilla/> References: <bug-272018-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D272018 Stefan E=C3=9Fer <se@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |se@FreeBSD.org --- Comment #2 from Stefan E=C3=9Fer <se@FreeBSD.org> --- Created attachment 242810 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D242810&action= =3Dedit Simpiified VPD parser The current VPD code uses a state machine to parse an assumed very flexible syntax, while the structure of valid VPD actually follows a quite strict fo= rmat that can be parsed by a very simple parser that hard-codes this structure. After fixing a kernel panic due to invalid VPD data that was not rejected by the existing parser, I have re-implemented the VPD parser based on the documented VPD definition. See review D34268 for the code that I had uploaded as a replacement (after adding many sanity checks to the state machine code that is meant to detect invalid VPD data). I'm not convinced that the current code's VPD checks catch all cases and fo= und that it is much easier to get a correct and safe parser by removing the unnecessary state machine. (The state machine would make sense, if the orde= r of elements in the VPD structure was less strict, but given the simple "linear" definition of VPD this flexibility stands in the way of easy detection of malformed VPD data.) The suggested replacement of the current VPD parser "knows" which element to expect next (with some segments being optional) and thus does not need any state variables. I'd appreciate a review of the patch, which is also attached to the PR (reb= ased to -CURRENT as of today). It has been tested with simulated VPD data (correct and malformed) and real= VPD device data - test code is available on request. --=20 You are receiving this mail because: You are the assignee for the bug.=
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