linux-dev/fs/configfs, branch master

configfs: fix a race in configfs_{,un}register_subsystem()

2022-02-22T17:30:28Z

When configfs_register_subsystem() or configfs_unregister_subsystem() is executing link_group() or unlink_group(), it is possible that two processes add or delete list concurrently. Some unfortunate interleavings of them can cause kernel panic. One of cases is: A --> B --> C --> D A <-- B <-- C <-- D delete list_head *B | delete list_head *C --------------------------------|----------------------------------- configfs_unregister_subsystem | configfs_unregister_subsystem unlink_group | unlink_group unlink_obj | unlink_obj list_del_init | list_del_init __list_del_entry | __list_del_entry __list_del | __list_del // next == C | next->prev = prev | | next->prev = prev prev->next = next | | // prev == B | prev->next = next Fix this by adding mutex when calling link_group() or unlink_group(), but parent configfs_subsystem is NULL when config_item is root. So I create a mutex configfs_subsystem_mutex. Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem") Signed-off-by: ChenXiaoSong Signed-off-by: Laibin Qiu Signed-off-by: Christoph Hellwig

fsnotify: fix fsnotify hooks in pseudo filesystems

2022-01-24T13:17:02Z

Commit 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify will have access to a positive dentry. This allowed a race where opening the deleted file via cached dentry is now possible after receiving the IN_DELETE event. To fix the regression in pseudo filesystems, convert d_delete() calls to d_drop() (see commit 46c46f8df9aa ("devpts_pty_kill(): don't bother with d_delete()") and move the fsnotify hook after d_drop(). Add a missing fsnotify_unlink() hook in nfsdfs that was found during the audit of fsnotify hooks in pseudo filesystems. Note that the fsnotify hooks in simple_recursive_removal() follow d_invalidate(), so they require no change. Link: https://lore.kernel.org/r/20220120215305.282577-2-amir73il@gmail.com Reported-by: Ivan Delalande Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/ Fixes: 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()") Cc: stable@vger.kernel.org # v5.3+ Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara

configfs: fix a race in configfs_lookup()

2021-08-25T05:58:49Z

When configfs_lookup() is executing list_for_each_entry(), it is possible that configfs_dir_lseek() is calling list_del(). Some unfortunate interleavings of them can cause a kernel NULL pointer dereference error Thread 1 Thread 2 //configfs_dir_lseek() //configfs_lookup() list_del(&cursor->s_sibling); list_for_each_entry(sd, ...) Fix this by grabbing configfs_dirent_lock in configfs_lookup() while iterating ->s_children. Signed-off-by: Sishuai Gong Signed-off-by: Christoph Hellwig

configfs: fold configfs_attach_attr into configfs_lookup

2021-08-25T05:58:46Z

This makes it more clear what gets added to the dcache and prepares for an additional locking fix. Signed-off-by: Christoph Hellwig

configfs: simplify the configfs_dirent_is_ready

2021-08-25T05:43:55Z

Return the error directly instead of using a goto. Signed-off-by: Christoph Hellwig

configfs: return -ENAMETOOLONG earlier in configfs_lookup

2021-08-25T05:42:44Z

Just like most other file systems: get the simple checks out of the way first. Signed-off-by: Christoph Hellwig

configfs: restore the kernel v5.13 text attribute write behavior

2021-08-09T14:56:00Z

Instead of appending new text attribute data at the offset specified by the write() system call, only pass the newly written data to the .store() callback. Reported-by: Bodo Stroesser Tested-by: Bodo Stroesser Signed-off-by: Bart Van Assche Signed-off-by: Christoph Hellwig

configfs: fix the read and write iterators

2021-07-13T18:56:24Z

Commit 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter methods") changed the simple_read_from_buffer() calls into copy_to_iter() calls and the simple_write_to_buffer() calls into copy_from_iter() calls. The simple*buffer() methods update the file offset (*ppos) but the read and write iterators not yet. Make the read and write iterators update the file offset (iocb->ki_pos). This patch has been tested as follows: # modprobe target_core_user # dd if=/sys/kernel/config/target/dbroot bs=1 /var/target 12+0 records in 12+0 records out 12 bytes copied, 9.5539e-05 s, 126 kB/s # cd /sys/kernel/config/acpi/table # mkdir test # cd test # dmesg -c >/dev/null; printf 'SSDT\x8\0\0\0abcdefghijklmnopqrstuvwxyz' | dd of=aml bs=1; dmesg -c 34+0 records in 34+0 records out 34 bytes copied, 0.010627 s, 3.2 kB/s [ 261.056551] ACPI configfs: invalid table length Reported-by: Yanko Kaneti Cc: Yanko Kaneti Fixes: 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter methods") Signed-off-by: Bart Van Assche Signed-off-by: Christoph Hellwig

Merge tag 'configfs-5.13' of git://git.infradead.org/users/hch/configfs

2021-07-02T21:13:21Z

Pull configfs updates from Christoph Hellwig: - fix a memleak in configfs_release_bin_file (Chung-Chiang Cheng) - implement the .read_iter and .write_iter (Bart Van Assche) - minor cleanups (Bart Van Assche, me) * tag 'configfs-5.13' of git://git.infradead.org/users/hch/configfs: configfs: simplify configfs_release_bin_file configfs: fix memleak in configfs_release_bin_file configfs: implement the .read_iter and .write_iter methods configfs: drop pointless kerneldoc comments configfs: fix the kerneldoc comment for configfs_create_bin_file

fs: move ramfs_aops to libfs

2021-06-29T17:53:48Z

Move the ramfs aops to libfs and reuse them for kernfs and configfs. Thosw two did not wire up ->set_page_dirty before and now get __set_page_dirty_no_writeback, which is the right one for no-writeback address_space usage. Drop the now unused exports of the libfs helpers only used for ramfs-style pagecache usage. Link: https://lkml.kernel.org/r/20210614061512.3966143-3-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Greg Kroah-Hartman Reviewed-by: Jan Kara Cc: Al Viro Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds