Date: Sat, 22 Nov 2025 14:53:34 +0000 From: Alan Somers <asomers@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 3b8ac7895d7b - stable/14 - fusefs: fix page fault triggered by async notification when unmounted Message-ID: <6921ce6e.33004.50bd7f9@gitrepo.freebsd.org>
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The branch stable/14 has been updated by asomers: URL: https://cgit.FreeBSD.org/src/commit/?id=3b8ac7895d7bcb66aaa83d2667b8e3de17f02ede commit 3b8ac7895d7bcb66aaa83d2667b8e3de17f02ede Author: Alan Somers <asomers@FreeBSD.org> AuthorDate: 2025-10-26 00:37:02 +0000 Commit: Alan Somers <asomers@FreeBSD.org> CommitDate: 2025-11-22 14:53:03 +0000 fusefs: fix page fault triggered by async notification when unmounted A FUSE daemon can send asynchronous notification to the kernel in order to, for example, invalidate an inode's cache. Fix a page fault that can happen if the file system isn't yet mounted, or is already unmounted, when that notification arrives. PR: 290519 Reviewed by: emaste Differential Revision: https://reviews.freebsd.org/D53356 (cherry picked from commit 5d42c8813976af484fd3e9a896c7839ba27ca764) --- sys/fs/fuse/fuse_device.c | 6 +++++ tests/sys/fs/fusefs/mockfs.cc | 4 +++- tests/sys/fs/fusefs/mockfs.hh | 4 +++- tests/sys/fs/fusefs/notify.cc | 56 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 68 insertions(+), 2 deletions(-) diff --git a/sys/fs/fuse/fuse_device.c b/sys/fs/fuse/fuse_device.c index 26f764f1939c..8f557a51e82b 100644 --- a/sys/fs/fuse/fuse_device.c +++ b/sys/fs/fuse/fuse_device.c @@ -542,6 +542,12 @@ fuse_device_write(struct cdev *dev, struct uio *uio, int ioflag) } else if (ohead.unique == 0){ /* unique == 0 means asynchronous notification */ SDT_PROBE1(fusefs, , device, fuse_device_write_notify, &ohead); + if (data->mp == NULL) { + SDT_PROBE2(fusefs, , device, trace, 1, + "asynchronous notification before mount" + " or after unmount"); + return (ENODEV); + } mp = data->mp; vfs_ref(mp); err = vfs_busy(mp, 0); diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc index f48165f6a151..4fa802cd7250 100644 --- a/tests/sys/fs/fusefs/mockfs.cc +++ b/tests/sys/fs/fusefs/mockfs.cc @@ -828,10 +828,12 @@ void MockFS::loop() { } } -int MockFS::notify_inval_entry(ino_t parent, const char *name, size_t namelen) +int MockFS::notify_inval_entry(ino_t parent, const char *name, size_t namelen, + int expected_errno) { std::unique_ptr<mockfs_buf_out> out(new mockfs_buf_out); + out->expected_errno = expected_errno; out->header.unique = 0; /* 0 means asynchronous notification */ out->header.error = FUSE_NOTIFY_INVAL_ENTRY; out->body.inval_entry.parent = parent; diff --git a/tests/sys/fs/fusefs/mockfs.hh b/tests/sys/fs/fusefs/mockfs.hh index ba6f7fded9d0..4b0628d34dd7 100644 --- a/tests/sys/fs/fusefs/mockfs.hh +++ b/tests/sys/fs/fusefs/mockfs.hh @@ -390,8 +390,10 @@ class MockFS { * @param parent Parent directory's inode number * @param name name of dirent to invalidate * @param namelen size of name, including the NUL + * @param expected_errno The error that write() should return */ - int notify_inval_entry(ino_t parent, const char *name, size_t namelen); + int notify_inval_entry(ino_t parent, const char *name, size_t namelen, + int expected_errno = 0); /* * Send an asynchronous notification to invalidate an inode's cached diff --git a/tests/sys/fs/fusefs/notify.cc b/tests/sys/fs/fusefs/notify.cc index 1e22bde13db7..d370a1e6e706 100644 --- a/tests/sys/fs/fusefs/notify.cc +++ b/tests/sys/fs/fusefs/notify.cc @@ -385,6 +385,27 @@ TEST_F(Notify, inval_inode_with_clean_cache) leak(fd); } +/* + * Attempting to invalidate an entry or inode after unmounting should fail, but + * nothing bad should happen. + * https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=290519 + */ +TEST_F(Notify, notify_after_unmount) +{ + const static char *name = "foo"; + struct inval_entry_args iea; + + expect_destroy(0); + + m_mock->unmount(); + + iea.mock = m_mock; + iea.parent = FUSE_ROOT_ID; + iea.name = name; + iea.namelen = strlen(name); + iea.mock->notify_inval_entry(iea.parent, iea.name, iea.namelen, ENODEV); +} + /* FUSE_NOTIFY_STORE with a file that's not in the entry cache */ /* disabled because FUSE_NOTIFY_STORE is not yet implemented */ TEST_F(Notify, DISABLED_store_nonexistent) @@ -544,3 +565,38 @@ TEST_F(NotifyWriteback, inval_inode_attrs_only) leak(fd); } + +/* + * Attempting asynchronous invalidation of an Entry before mounting the file + * system should fail, but nothing bad should happen. + * + * Note that invalidating an inode before mount goes through the same path, and + * is not separately tested. + * + * https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=290519 + */ +TEST(PreMount, inval_entry_before_mount) +{ + const static char name[] = "foo"; + size_t namelen = strlen(name); + struct mockfs_buf_out *out; + int r; + int fuse_fd; + + fuse_fd = open("/dev/fuse", O_CLOEXEC | O_RDWR); + ASSERT_GE(fuse_fd, 0) << strerror(errno); + + out = new mockfs_buf_out; + out->header.unique = 0; /* 0 means asynchronous notification */ + out->header.error = FUSE_NOTIFY_INVAL_ENTRY; + out->body.inval_entry.parent = FUSE_ROOT_ID; + out->body.inval_entry.namelen = namelen; + strlcpy((char*)&out->body.bytes + sizeof(out->body.inval_entry), + name, sizeof(out->body.bytes) - sizeof(out->body.inval_entry)); + out->header.len = sizeof(out->header) + sizeof(out->body.inval_entry) + + namelen; + r = write(fuse_fd, out, out->header.len); + EXPECT_EQ(-1, r); + EXPECT_EQ(ENODEV, errno); + delete out; +}help
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