4.4-stable patches

added patches:
	vt-selection-push-sel_lock-up.patch

diff --git a/queue-4.4/series b/queue-4.4/series
index 2137d873ce2a6d4a6f800f1f502ef2aeb6ab2adf..6cbd26933318228f8d43fe466d664e201f264185 100644 (file)
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -56,3 +56,4 @@ vgacon-fix-a-uaf-in-vgacon_invert_region.patch
 fat-fix-uninit-memory-access-for-partial-initialized-inode.patch
 vt-selection-close-sel_buffer-race.patch
 vt-selection-push-console-lock-down.patch
+vt-selection-push-sel_lock-up.patch

diff --git a/queue-4.4/vt-selection-push-sel_lock-up.patch b/queue-4.4/vt-selection-push-sel_lock-up.patch
new file mode 100644 (file)
index 0000000..fd5ebce
--- /dev/null
+++ b/queue-4.4/vt-selection-push-sel_lock-up.patch
@@ -0,0 +1,145 @@
+From e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2 Mon Sep 17 00:00:00 2001
+From: Jiri Slaby <jslaby@suse.cz>
+Date: Fri, 28 Feb 2020 12:54:06 +0100
+Subject: vt: selection, push sel_lock up
+
+From: Jiri Slaby <jslaby@suse.cz>
+
+commit e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2 upstream.
+
+sel_lock cannot nest in the console lock. Thanks to syzkaller, the
+kernel states firmly:
+
+> WARNING: possible circular locking dependency detected
+> 5.6.0-rc3-syzkaller #0 Not tainted
+> ------------------------------------------------------
+> syz-executor.4/20336 is trying to acquire lock:
+> ffff8880a2e952a0 (&tty->termios_rwsem){++++}, at: tty_unthrottle+0x22/0x100 drivers/tty/tty_ioctl.c:136
+>
+> but task is already holding lock:
+> ffffffff89462e70 (sel_lock){+.+.}, at: paste_selection+0x118/0x470 drivers/tty/vt/selection.c:374
+>
+> which lock already depends on the new lock.
+>
+> the existing dependency chain (in reverse order) is:
+>
+> -> #2 (sel_lock){+.+.}:
+>        mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118
+>        set_selection_kernel+0x3b8/0x18a0 drivers/tty/vt/selection.c:217
+>        set_selection_user+0x63/0x80 drivers/tty/vt/selection.c:181
+>        tioclinux+0x103/0x530 drivers/tty/vt/vt.c:3050
+>        vt_ioctl+0x3f1/0x3a30 drivers/tty/vt/vt_ioctl.c:364
+
+This is ioctl(TIOCL_SETSEL).
+Locks held on the path: console_lock -> sel_lock
+
+> -> #1 (console_lock){+.+.}:
+>        console_lock+0x46/0x70 kernel/printk/printk.c:2289
+>        con_flush_chars+0x50/0x650 drivers/tty/vt/vt.c:3223
+>        n_tty_write+0xeae/0x1200 drivers/tty/n_tty.c:2350
+>        do_tty_write drivers/tty/tty_io.c:962 [inline]
+>        tty_write+0x5a1/0x950 drivers/tty/tty_io.c:1046
+
+This is write().
+Locks held on the path: termios_rwsem -> console_lock
+
+> -> #0 (&tty->termios_rwsem){++++}:
+>        down_write+0x57/0x140 kernel/locking/rwsem.c:1534
+>        tty_unthrottle+0x22/0x100 drivers/tty/tty_ioctl.c:136
+>        mkiss_receive_buf+0x12aa/0x1340 drivers/net/hamradio/mkiss.c:902
+>        tty_ldisc_receive_buf+0x12f/0x170 drivers/tty/tty_buffer.c:465
+>        paste_selection+0x346/0x470 drivers/tty/vt/selection.c:389
+>        tioclinux+0x121/0x530 drivers/tty/vt/vt.c:3055
+>        vt_ioctl+0x3f1/0x3a30 drivers/tty/vt/vt_ioctl.c:364
+
+This is ioctl(TIOCL_PASTESEL).
+Locks held on the path: sel_lock -> termios_rwsem
+
+> other info that might help us debug this:
+>
+> Chain exists of:
+>   &tty->termios_rwsem --> console_lock --> sel_lock
+
+Clearly. From the above, we have:
+ console_lock -> sel_lock
+ sel_lock -> termios_rwsem
+ termios_rwsem -> console_lock
+
+Fix this by reversing the console_lock -> sel_lock dependency in
+ioctl(TIOCL_SETSEL). First, lock sel_lock, then console_lock.
+
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Reported-by: syzbot+26183d9746e62da329b8@syzkaller.appspotmail.com
+Fixes: 07e6124a1a46 ("vt: selection, close sel_buffer race")
+Cc: stable <stable@vger.kernel.org>
+Link: https://lore.kernel.org/r/20200228115406.5735-2-jslaby@suse.cz
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/tty/vt/selection.c |   16 +++++++---------
+ 1 file changed, 7 insertions(+), 9 deletions(-)
+
+--- a/drivers/tty/vt/selection.c
++++ b/drivers/tty/vt/selection.c
+@@ -205,7 +205,6 @@ static int __set_selection(const struct
+               pe = tmp;
+       }
+ 
+-      mutex_lock(&sel_lock);
+       if (sel_cons != vc_cons[fg_console].d) {
+               clear_selection();
+               sel_cons = vc_cons[fg_console].d;
+@@ -251,10 +250,9 @@ static int __set_selection(const struct
+                       break;
+               case TIOCL_SELPOINTER:
+                       highlight_pointer(pe);
+-                      goto unlock;
++                      return 0;
+               default:
+-                      ret = -EINVAL;
+-                      goto unlock;
++                      return -EINVAL;
+       }
+ 
+       /* remove the pointer */
+@@ -276,7 +274,7 @@ static int __set_selection(const struct
+       else if (new_sel_start == sel_start)
+       {
+               if (new_sel_end == sel_end)     /* no action required */
+-                      goto unlock;
++                      return 0;
+               else if (new_sel_end > sel_end) /* extend to right */
+                       highlight(sel_end + 2, new_sel_end);
+               else                            /* contract from right */
+@@ -303,8 +301,7 @@ static int __set_selection(const struct
+       if (!bp) {
+               printk(KERN_WARNING "selection: kmalloc() failed\n");
+               clear_selection();
+-              ret = -ENOMEM;
+-              goto unlock;
++              return -ENOMEM;
+       }
+       kfree(sel_buffer);
+       sel_buffer = bp;
+@@ -329,8 +326,7 @@ static int __set_selection(const struct
+               }
+       }
+       sel_buffer_lth = bp - sel_buffer;
+-unlock:
+-      mutex_unlock(&sel_lock);
++
+       return ret;
+ }
+ 
+@@ -338,9 +334,11 @@ int set_selection(const struct tiocl_sel
+ {
+       int ret;
+ 
++      mutex_lock(&sel_lock);
+       console_lock();
+       ret = __set_selection(v, tty);
+       console_unlock();
++      mutex_unlock(&sel_lock);
+ 
+       return ret;
+ }