Date: Tue, 18 Jan 2022 01:44:29 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259071 --- Comment #24 from commit-hook@FreeBSD.org --- A commit in branch stable/12 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=c85846ea3ea531affb80edb2c982017d35b5a40f commit c85846ea3ea531affb80edb2c982017d35b5a40f Author: Alan Somers <asomers@FreeBSD.org> AuthorDate: 2021-11-29 02:17:34 +0000 Commit: Alan Somers <asomers@FreeBSD.org> CommitDate: 2022-01-18 01:23:34 +0000 Fix a race in fusefs that can corrupt a file's size. VOPs like VOP_SETATTR can change a file's size, with the vnode exclusively locked. But VOPs like VOP_LOOKUP look up the file size from the server without the vnode locked. So a race is possible. For example: 1) One thread calls VOP_SETATTR to truncate a file. It locks the vnode and sends FUSE_SETATTR to the server. 2) A second thread calls VOP_LOOKUP and fetches the file's attributes from the server. Then it blocks trying to acquire the vnode lock. 3) FUSE_SETATTR returns and the first thread releases the vnode lock. 4) The second thread acquires the vnode lock and caches the file's attributes, which are now out-of-date. Fix this race by recording a timestamp in the vnode of the last time that its filesize was modified. Check that timestamp during VOP_LOOKUP and VFS_VGET. If it's newer than the time at which FUSE_LOOKUP was issued to the server, ignore the attributes returned by FUSE_LOOKUP. PR: 259071 Reported by: Agata <email@example.com> Reviewed by: pfg Differential Revision: https://reviews.freebsd.org/D33158 (cherry picked from commit 13d593a5b060cf7be40acfa2ca9dc9e0e2339a31) sys/fs/fuse/fuse_internal.c | 5 + sys/fs/fuse/fuse_io.c | 5 +- sys/fs/fuse/fuse_node.c | 5 +- sys/fs/fuse/fuse_node.h | 6 + sys/fs/fuse/fuse_vfsops.c | 13 +- sys/fs/fuse/fuse_vnops.c | 15 +- tests/sys/fs/fusefs/Makefile | 1 + tests/sys/fs/fusefs/last_local_modify.cc (new) | 423 +++++++++++++++++++++++++ 8 files changed, 466 insertions(+), 7 deletions(-) -- You are receiving this mail because: You are the assignee for the bug.