fusefs: validate servers' error values
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Authored by asomers on Apr 15 2022, 7:09 PM.

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Reviewers

emaste
pfg

Commits

rG73e02a370e52: fusefs: validate servers' error values
rGef0e12d5656a: fusefs: validate servers' error values
rG155ac516c60f: fusefs: validate servers' error values

Summary

Formerly fusefs would pass up the stack any error value returned by the
fuse server. However, some values aren't valid for userland, but have
special meanings within the kernel. One of these, EJUSTRETURN, could
cause a kernel page fault if the server returned it in response to
FUSE_LOOKUP. Fix by validating all errors returned by the server.

Also, fix a data lifetime bug in the FUSE_DESTROY test.

PR: 263220
Reported by: Robert Morris <rtm@lcs.mit.edu>
MFC after: 3 weeks
Sponsored by: Axcient

Test Plan

Test case added

Diff Detail

Repository

rG FreeBSD src repository

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Unit

Tests Not Applicable

Event Timeline

asomers created this revision.Apr 15 2022, 7:09 PM

Herald added a subscriber: imp. · View Herald TranscriptApr 15 2022, 7:09 PM

asomers requested review of this revision.Apr 15 2022, 7:09 PM

Harbormaster completed remote builds in B45190: Diff 105055.Apr 15 2022, 7:09 PM

emaste added inline comments.Apr 15 2022, 7:13 PM

sys/fs/fuse/fuse_device.c
524–525	is this the same in each branch?

asomers added inline comments.Apr 15 2022, 7:32 PM

sys/fs/fuse/fuse_device.c
524–525	Almost. The memcpy part is the same, but the tk_aw_handler part isn't. And memcpy needs to happen first. Annoyingly repetitive I know, but I couldn't find a way to remove the repetition that didn't actually increase total lines.