kernel/linux.git/drivers/tty/tty_io.c, branch v3.18.100

tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)

2016-02-15T20:42:32+00:00

[ Upstream commit 5c17c861a357e9458001f021a7afa7aab9937439 ] ioctl(TIOCGETD) retrieves the line discipline id directly from the ldisc because the line discipline id (c_line) in termios is untrustworthy; userspace may have set termios via ioctl(TCSETS*) without actually changing the line discipline via ioctl(TIOCSETD). However, directly accessing the current ldisc via tty->ldisc is unsafe; the ldisc ptr dereferenced may be stale if the line discipline is changing via ioctl(TIOCSETD) or hangup. Wait for the line discipline reference (just like read() or write()) to retrieve the "current" line discipline id. Cc: Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

tty: fix up atime/mtime mess, take four

2015-03-14T19:37:28+00:00

commit f0bf0bd07943bfde8f5ac39a32664810a379c7d3 upstream. This problem was taken care of three times already in * b0de59b5733d18b0d1974a060860a8b5c1b36a2e (TTY: do not update atime/mtime on read/write), * 37b7f3c76595e23257f61bd80b223de8658617ee (TTY: fix atime/mtime regression), and * b0b885657b6c8ef63a46bc9299b2a7715d19acde (tty: fix up atime/mtime mess, take three) But it still misses one point. As John Paul correctly points out, we do not care about setting date. If somebody ever changes wall time backwards (by mistake for example), tty timestamps are never updated until the original wall time passes. So check the absolute difference of times and if it large than "8 seconds or so", always update the time. That means we will update immediatelly when changing time. Ergo, CAP_SYS_TIME can foul the check, but it was always that way. Thanks John for serving me this so nicely debugged. Signed-off-by: Jiri Slaby Reported-by: John Paul Perry Acked-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

tty: Prevent "read/write wait queue active!" log flooding

2014-11-06T00:14:09+00:00

Only print one warning when a task is on the read_wait or write_wait wait queue at final tty release. Cc: # 3.4.x+ Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Fix high cpu load if tty is unreleaseable

2014-11-06T00:14:09+00:00

Kernel oops can cause the tty to be unreleaseable (for example, if n_tty_read() crashes while on the read_wait queue). This will cause tty_release() to endlessly loop without sleeping. Use a killable sleep timeout which grows by 2n+1 jiffies over the interval [0, 120 secs.) and then jumps to forever (but still killable). NB: killable just allows for the task to be rewoken manually, not to be terminated. Cc: # since before 2.6.32 Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

Merge tag 'locks-v3.18-1' of git://git.samba.org/jlayton/linux

2014-10-11T17:21:34+00:00

Pull file locking related changes from Jeff Layton: "This release is a little more busy for file locking changes than the last: - a set of patches from Kinglong Mee to fix the lockowner handling in knfsd - a pile of cleanups to the internal file lease API. This should get us a bit closer to allowing for setlease methods that can block. There are some dependencies between mine and Bruce's trees this cycle, and I based my tree on top of the requisite patches in Bruce's tree" * tag 'locks-v3.18-1' of git://git.samba.org/jlayton/linux: (26 commits) locks: fix fcntl_setlease/getlease return when !CONFIG_FILE_LOCKING locks: flock_make_lock should return a struct file_lock (or PTR_ERR) locks: set fl_owner for leases to filp instead of current->files locks: give lm_break a return value locks: __break_lease cleanup in preparation of allowing direct removal of leases locks: remove i_have_this_lease check from __break_lease locks: move freeing of leases outside of i_lock locks: move i_lock acquisition into generic_*_lease handlers locks: define a lm_setup handler for leases locks: plumb a "priv" pointer into the setlease routines nfsd: don't keep a pointer to the lease in nfs4_file locks: clean up vfs_setlease kerneldoc comments locks: generic_delete_lease doesn't need a file_lock at all nfsd: fix potential lease memory leak in nfs4_setlease locks: close potential race in lease_get_mtime security: make security_file_set_fowner, f_setown and __f_setown void return locks: consolidate "nolease" routines locks: remove lock_may_read and lock_may_write lockd: rip out deferred lock handling from testlock codepath NFSD: Get reference of lockowner when coping file_lock ...

tty: Move and rename send_prio_char() as tty_send_xchar()

2014-09-24T04:19:35+00:00

Relocate the file-scope function, send_prio_char(), as a global helper tty_send_xchar(). Remove the global declarations for tty_write_lock()/tty_write_unlock(), as these are file-scope only now. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Move packet mode flow control notifications to pty driver

2014-09-24T04:19:35+00:00

When a master pty is set to packet mode, flow control changes to the slave pty cause notifications to the master pty via reads and polls. However, these tests are occurring for all ttys, not just ptys. Implement flow control packet mode notifications in the pty driver. Only the slave side implements the flow control handlers since packet mode is asymmetric; the master pty receives notifications for slave-side changes, but not vice versa. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Serialize tty flow control changes with flow_lock

2014-09-24T04:19:35+00:00

Without serialization, the flow control state can become inverted wrt. the actual hardware state. For example, CPU 0 | CPU 1 stop_tty() | lock ctrl_lock | tty->stopped = 1 | unlock ctrl_lock | | start_tty() | lock ctrl_lock | tty->stopped = 0 | unlock ctrl_lock | driver->start() driver->stop() | In this case, the flow control state now indicates the tty has been started, but the actual hardware state has actually been stopped. Introduce tty->flow_lock spinlock to serialize tty flow control changes. Split out unlocked __start_tty()/__stop_tty() flavors for use by ioctl(TCXONC) in follow-on patch. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

security: make security_file_set_fowner, f_setown and __f_setown void return

2014-09-09T20:01:36+00:00

security_file_set_fowner always returns 0, so make it f_setown and __f_setown void return functions and fix up the error handling in the callers. Cc: linux-security-module@vger.kernel.org Signed-off-by: Jeff Layton Reviewed-by: Christoph Hellwig

tty: Fix potential use after free in release_one_tty

2014-09-08T22:55:25+00:00

In case if we're releasing the last tty reference the following call sequence is possible tty_driver_kref_put destruct_tty_driver kfree(driver); where @driver is used in next module_put call, which leads to | [ 285.964007] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 | [ 285.964007] Workqueue: events release_one_tty | [ 285.964007] task: ffff8800cc7ea5f0 ti: ffff8800cb800000 task.ti: ffff8800cb800000 | [ 285.964007] RIP: 0010:[] [] module_put+0x24/0xf4 | [ 285.964007] RSP: 0018:ffff8800cb801d48 EFLAGS: 00010213 | [ 285.964007] RAX: ffff8800cb801fd8 RBX: ffff8800ca3429d0 RCX: ffff8800cb1db400 | [ 285.964007] RDX: 0000000000000000 RSI: ffffffff817349c1 RDI: 0000000000000001 | [ 285.964007] RBP: ffff8800cb801d60 R08: ffff8800cd632b40 R09: 0000000000000000 | [ 285.964007] R10: 00000000ffffffff R11: ffff88011f40a000 R12: 6b6b6b6b6b6b6b6b | [ 285.964007] R13: ffff8800ca342520 R14: 0000000000000000 R15: ffff88011f5d8200 | [ 285.964007] FS: 0000000000000000(0000) GS:ffff88011f400000(0000) knlGS:0000000000000000 | [ 285.964007] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b | [ 285.964007] CR2: 00007faf5229d090 CR3: 0000000001c0b000 CR4: 00000000000006f0 | [ 285.964007] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 | [ 285.964007] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 | [ 285.964007] Stack: | [ 285.964007] ffff8800ca3429d0 ffff8800ca342a30 ffff8800ca342520 ffff8800cb801d88 | [ 285.964007] ffffffff8146554a ffff8800cc77cc78 ffff8800ca3429d0 ffff88011f5d3800 | [ 285.964007] ffff8800cb801e08 ffffffff810683c1 ffffffff810682ff 0000000000000046 | [ 285.964007] Call Trace: | [ 285.964007] [] release_one_tty+0x54/0xa3 | [ 285.964007] [] process_one_work+0x223/0x404 | [ 285.964007] [] ? process_one_work+0x161/0x404 | [ 285.964007] [] worker_thread+0x136/0x205 | [ 285.964007] [] ? rescuer_thread+0x26a/0x26a | [ 285.964007] [] kthread+0xa2/0xaa | [ 285.964007] [] ? trace_hardirqs_on_caller+0x16/0x1eb | [ 285.964007] [] ? __kthread_parkme+0x65/0x65 | [ 285.964007] [] ret_from_fork+0x7c/0xb0 | [ 285.964007] [] ? __kthread_parkme+0x65/0x65 | [ 285.964007] Code: 09 00 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 85 ff 48 89 e5 41 55 41 54 49 89 fc 53 0f 84 d3 00 | 00 00 bf 01 00 00 00 e8 d0 a1 fc ff <49> 8b 84 24 50 02 00 00 65 48 ff 40 08 4c 8b 6d 08 0f 1f 44 00 so simply keep a local reference to the module owner and use it later. CC: Pavel Emelyanov CC: Jiri Slaby CC: Greg Kroah-Hartman Signed-off-by: Cyrill Gorcunov Signed-off-by: Greg Kroah-Hartman