Date: Thu, 21 Oct 2021 21:24:07 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 259071] Read past EoF in NFS client and fusefs Message-ID: <bug-259071-227-xIWV06K63h@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-259071-227@https.bugs.freebsd.org/bugzilla/> References: <bug-259071-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D259071 --- Comment #3 from Rick Macklem <rmacklem@FreeBSD.org> --- Well, I think I've figured out what the breakage is for the NFS client. I'll leave it to asomers@ to decide if fuse suffers from the same problem. To be honest, I think this bug has existed in the BSD NFS client *forever* (as in, since I first wrote NFS client code for 4.3BSD in 1986, believe it or not;-). Here's what seems to happen: Child Parent - does stat() - does VOP_LOOKUP(), which does the Lookup RPC with the directory vnode locked - does ftruncate(), acquiring --> acquires file handle and exclusive vnode lock on file vnode attributes, including Size, valid at this point in time - blocks waiting for locked file vnode - does VOP_SETATTR() of Size, changing the file's size - releases the file vnode - acquires file vnode and fills in now stale attributes including the old wrong Size - does a read() which returns wrong data size I am working on a patch, which I plan to discuss with asomers@ off list. I will put a patch here as an attachment if/when I have one. --=20 You are receiving this mail because: You are the assignee for the bug.=
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