kernel/linux.git, branch v4.4.173

Linux 4.4.173

2019-02-06T18:43:08+00:00

fs: don't scan the inode cache before SB_BORN is set

2019-02-06T18:43:08+00:00

commit 79f546a696bff2590169fb5684e23d65f4d9f591 upstream. We recently had an oops reported on a 4.14 kernel in xfs_reclaim_inodes_count() where sb->s_fs_info pointed to garbage and so the m_perag_tree lookup walked into lala land. It produces an oops down this path during the failed mount: radix_tree_gang_lookup_tag+0xc4/0x130 xfs_perag_get_tag+0x37/0xf0 xfs_reclaim_inodes_count+0x32/0x40 xfs_fs_nr_cached_objects+0x11/0x20 super_cache_count+0x35/0xc0 shrink_slab.part.66+0xb1/0x370 shrink_node+0x7e/0x1a0 try_to_free_pages+0x199/0x470 __alloc_pages_slowpath+0x3a1/0xd20 __alloc_pages_nodemask+0x1c3/0x200 cache_grow_begin+0x20b/0x2e0 fallback_alloc+0x160/0x200 kmem_cache_alloc+0x111/0x4e0 The problem is that the superblock shrinker is running before the filesystem structures it depends on have been fully set up. i.e. the shrinker is registered in sget(), before ->fill_super() has been called, and the shrinker can call into the filesystem before fill_super() does it's setup work. Essentially we are exposed to both use-after-free and use-before-initialisation bugs here. To fix this, add a check for the SB_BORN flag in super_cache_count. In general, this flag is not set until ->fs_mount() completes successfully, so we know that it is set after the filesystem setup has completed. This matches the trylock_super() behaviour which will not let super_cache_scan() run if SB_BORN is not set, and hence will not allow the superblock shrinker from entering the filesystem while it is being set up or after it has failed setup and is being torn down. Cc: stable@kernel.org Signed-Off-By: Dave Chinner Signed-off-by: Al Viro Signed-off-by: Aaron Lu Signed-off-by: Greg Kroah-Hartman

mm: migrate: don't rely on __PageMovable() of newpage after unlocking it

2019-02-06T18:43:08+00:00

commit e0a352fabce61f730341d119fbedf71ffdb8663f upstream. We had a race in the old balloon compaction code before b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature") refactored it that became visible after backporting 195a8c43e93d ("virtio-balloon: deflate via a page list") without the refactoring. The bug existed from commit d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management") till b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature"). d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management") was backported to 3.12, so the broken kernels are stable kernels [3.12 - 4.7]. There was a subtle race between dropping the page lock of the newpage in __unmap_and_move() and checking for __is_movable_balloon_page(newpage). Just after dropping this page lock, virtio-balloon could go ahead and deflate the newpage, effectively dequeueing it and clearing PageBalloon, in turn making __is_movable_balloon_page(newpage) fail. This resulted in dropping the reference of the newpage via putback_lru_page(newpage) instead of put_page(newpage), leading to page->lru getting modified and a !LRU page ending up in the LRU lists. With 195a8c43e93d ("virtio-balloon: deflate via a page list") backported, one would suddenly get corrupted lists in release_pages_balloon(): - WARNING: CPU: 13 PID: 6586 at lib/list_debug.c:59 __list_del_entry+0xa1/0xd0 - list_del corruption. prev->next should be ffffe253961090a0, but was dead000000000100 Nowadays this race is no longer possible, but it is hidden behind very ugly handling of __ClearPageMovable() and __PageMovable(). __ClearPageMovable() will not make __PageMovable() fail, only PageMovable(). So the new check (__PageMovable(newpage)) will still hold even after newpage was dequeued by virtio-balloon. If anybody would ever change that special handling, the BUG would be introduced again. So instead, make it explicit and use the information of the original isolated page before migration. This patch can be backported fairly easy to stable kernels (in contrast to the refactoring). Link: http://lkml.kernel.org/r/20190129233217.10747-1-david@redhat.com Fixes: d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management") Signed-off-by: David Hildenbrand Reported-by: Vratislav Bendel Acked-by: Michal Hocko Acked-by: Rafael Aquini Cc: Mel Gorman Cc: "Kirill A. Shutemov" Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Jan Kara Cc: Andrea Arcangeli Cc: Dominik Brodowski Cc: Matthew Wilcox Cc: Vratislav Bendel Cc: Rafael Aquini Cc: Konstantin Khlebnikov Cc: Minchan Kim Cc: [3.12 - 4.7] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: David Hildenbrand Signed-off-by: Greg Kroah-Hartman

drivers: core: Remove glue dirs from sysfs earlier

2019-02-06T18:43:08+00:00

commit 726e41097920a73e4c7c33385dcc0debb1281e18 upstream. For devices with a class, we create a "glue" directory between the parent device and the new device with the class name. This directory is never "explicitely" removed when empty however, this is left to the implicit sysfs removal done by kobject_release() when the object loses its last reference via kobject_put(). This is problematic because as long as it's not been removed from sysfs, it is still present in the class kset and in sysfs directory structure. The presence in the class kset exposes a use after free bug fixed by the previous patch, but the presence in sysfs means that until the kobject is released, which can take a while (especially with kobject debugging), any attempt at re-creating such as binding a new device for that class/parent pair, will result in a sysfs duplicate file name error. This fixes it by instead doing an explicit kobject_del() when the glue dir is empty, by keeping track of the number of child devices of the gluedir. This is made easy by the fact that all glue dir operations are done with a global mutex, and there's already a function (cleanup_glue_dir) called in all the right places taking that mutex that can be enhanced for this. It appears that this was in fact the intent of the function, but the implementation was wrong. Signed-off-by: Benjamin Herrenschmidt Acked-by: Linus Torvalds Signed-off-by: Zubin Mithra Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

cifs: Always resolve hostname before reconnecting

2019-02-06T18:43:07+00:00

commit 28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d upstream. In case a hostname resolves to a different IP address (e.g. long running mounts), make sure to resolve it every time prior to calling generic_ip_connect() in reconnect. Suggested-by: Steve French Signed-off-by: Paulo Alcantara Signed-off-by: Steve French Signed-off-by: Pavel Shilovsky Signed-off-by: Greg Kroah-Hartman

mm, oom: fix use-after-free in oom_kill_process

2019-02-06T18:43:07+00:00

commit cefc7ef3c87d02fc9307835868ff721ea12cc597 upstream. Syzbot instance running on upstream kernel found a use-after-free bug in oom_kill_process. On further inspection it seems like the process selected to be oom-killed has exited even before reaching read_lock(&tasklist_lock) in oom_kill_process(). More specifically the tsk->usage is 1 which is due to get_task_struct() in oom_evaluate_task() and the put_task_struct within for_each_thread() frees the tsk and for_each_thread() tries to access the tsk. The easiest fix is to do get/put across the for_each_thread() on the selected task. Now the next question is should we continue with the oom-kill as the previously selected task has exited? However before adding more complexity and heuristics, let's answer why we even look at the children of oom-kill selected task? The select_bad_process() has already selected the worst process in the system/memcg. Due to race, the selected process might not be the worst at the kill time but does that matter? The userspace can use the oom_score_adj interface to prefer children to be killed before the parent. I looked at the history but it seems like this is there before git history. Link: http://lkml.kernel.org/r/20190121215850.221745-1-shakeelb@google.com Reported-by: syzbot+7fbbfa368521945f0e3d@syzkaller.appspotmail.com Fixes: 6b0c81b3be11 ("mm, oom: reduce dependency on tasklist_lock") Signed-off-by: Shakeel Butt Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Cc: David Rientjes Cc: Johannes Weiner Cc: Tetsuo Handa Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

kernel/exit.c: release ptraced tasks before zap_pid_ns_processes

2019-02-06T18:43:07+00:00

commit 8fb335e078378c8426fabeed1ebee1fbf915690c upstream. Currently, exit_ptrace() adds all ptraced tasks in a dead list, then zap_pid_ns_processes() waits on all tasks in a current pidns, and only then are tasks from the dead list released. zap_pid_ns_processes() can get stuck on waiting tasks from the dead list. In this case, we will have one unkillable process with one or more dead children. Thanks to Oleg for the advice to release tasks in find_child_reaper(). Link: http://lkml.kernel.org/r/20190110175200.12442-1-avagin@gmail.com Fixes: 7c8bd2322c7f ("exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()") Signed-off-by: Andrei Vagin Signed-off-by: Oleg Nesterov Cc: "Eric W. Biederman" Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mmc: sdhci-iproc: handle mmc_of_parse() errors during probe

2019-02-06T18:43:07+00:00

commit 2bd44dadd5bfb4135162322fd0b45a174d4ad5bf upstream. We need to handle mmc_of_parse() errors during probe. This finally fixes the wifi regression on Raspberry Pi 3 series. In error case the wifi chip was permanently in reset because of the power sequence depending on the deferred probe of the GPIO expander. Fixes: b580c52d58d9 ("mmc: sdhci-iproc: add IPROC SDHCI driver") Cc: stable@vger.kernel.org Signed-off-by: Stefan Wahren Acked-by: Adrian Hunter Signed-off-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman

platform/x86: asus-nb-wmi: Drop mapping of 0x33 and 0x34 scan codes

2019-02-06T18:43:07+00:00

[ Upstream commit 71b12beaf12f21a53bfe100795d0797f1035b570 ] According to Asus firmware engineers, the meaning of these codes is only to notify the OS that the screen brightness has been turned on/off by the EC. This does not match the meaning of KEY_DISPLAYTOGGLE / KEY_DISPLAY_OFF, where userspace is expected to change the display brightness. Signed-off-by: João Paulo Rechi Vita Signed-off-by: Andy Shevchenko Signed-off-by: Sasha Levin

platform/x86: asus-nb-wmi: Map 0x35 to KEY_SCREENLOCK

2019-02-06T18:43:07+00:00

[ Upstream commit b3f2f3799a972d3863d0fdc2ab6287aef6ca631f ] When the OS registers to handle events from the display off hotkey the EC will send a notification with 0x35 for every key press, independent of the backlight state. The behavior of this key on Windows, with the ATKACPI driver from Asus installed, is turning off the backlight of all connected displays with a fading effect, and any cursor input or key press turning the backlight back on. The key press or cursor input that wakes up the display is also passed through to the application under the cursor or under focus. The key that matches this behavior the closest is KEY_SCREENLOCK. Signed-off-by: João Paulo Rechi Vita Signed-off-by: Andy Shevchenko Signed-off-by: Sasha Levin