From: Greg Kroah-Hartman Date: Mon, 9 Mar 2020 19:35:00 +0000 (+0100) Subject: 4.4-stable patches X-Git-Tag: v4.4.216~48 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4408f3b3df6672a8adb3cb1e804e8258fe2c0bbe;p=thirdparty%2Fkernel%2Fstable-queue.git 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 2137d873ce2..6cbd2693331 100644 --- 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 index 00000000000..fd5ebce85dc --- /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 +Date: Fri, 28 Feb 2020 12:54:06 +0100 +Subject: vt: selection, push sel_lock up + +From: Jiri Slaby + +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 +Reported-by: syzbot+26183d9746e62da329b8@syzkaller.appspotmail.com +Fixes: 07e6124a1a46 ("vt: selection, close sel_buffer race") +Cc: stable +Link: https://lore.kernel.org/r/20200228115406.5735-2-jslaby@suse.cz +Signed-off-by: Greg Kroah-Hartman + +--- + 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; + }