Jiri Slaby 7e3ba72e5b vt: keyboard, extend func_buf_lock to readers ... commit 82e61c3909 upstream. Both read-side users of func_table/func_buf need locking. Without that, one can easily confuse the code by repeatedly setting altering strings like: while (1) for (a = 0; a < 2; a++) { struct kbsentry kbs = {}; strcpy((char *)kbs.kb_string, a ? ".\n" : "88888\n"); ioctl(fd, KDSKBSENT, &kbs); } When that program runs, one can get unexpected output by holding F1 (note the unxpected period on the last line): . 88888 .8888 So protect all accesses to 'func_table' (and func_buf) by preexisting 'func_buf_lock'. It is easy in 'k_fn' handler as 'puts_queue' is expected not to sleep. On the other hand, KDGKBSENT needs a local (atomic) copy of the string because copy_to_user can sleep. Use already allocated, but unused 'kbs->kb_string' for that purpose. Note that the program above needs at least CAP_SYS_TTY_CONFIG. This depends on the previous patch and on the func_buf_lock lock added in commit 46ca3f735f (tty/vt: fix write/write race in ioctl(KDSKBSENT) handler) in 5.2. Likely fixes CVE-2020-25656. Cc: <stable@vger.kernel.org> Reported-by: Minh Yuan <yuanmingbuaa@gmail.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20201019085517.10176-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-11-05 11:08:50 +01:00
..
hvc	tty: hvcs: Don't NULL tty->driver_data until hvcs_cleanup()	2020-10-29 09:55:08 +01:00
ipwireless	tty: ipwireless: fix error handling	2020-10-30 10:38:31 +01:00
serdev	serdev: ttyport: restore client ops on deregistration	2020-02-28 16:38:49 +01:00
serial	serial: pl011: Fix lockdep splat when handling magic-sysrq interrupt	2020-11-05 11:08:34 +01:00
vt	vt: keyboard, extend func_buf_lock to readers	2020-11-05 11:08:50 +01:00
amiserial.c
cyclades.c
ehv_bytechan.c	tty: evh_bytechan: Fix out of bounds accesses	2020-04-23 10:30:23 +02:00
goldfish.c
isicom.c
Kconfig
Makefile
mips_ejtag_fdc.c
moxa.c
moxa.h
mxser.c
mxser.h
n_gsm.c	tty: n_gsm: Fix bogus i++ in gsm_data_kick	2020-06-25 15:32:57 +02:00
n_hdlc.c	tty: Don't block on IO when ldisc change is pending	2019-12-13 08:52:28 +01:00
n_null.c
n_r3964.c	tty: Don't block on IO when ldisc change is pending	2019-12-13 08:52:28 +01:00
n_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c	tty: Don't block on IO when ldisc change is pending	2019-12-13 08:52:28 +01:00
nozomi.c
pty.c	pty: do tty_flip_buffer_push without port->lock in pty_write	2020-10-29 09:55:08 +01:00
rocket_int.h
rocket.c	tty: rocket, avoid OOB access	2020-04-29 16:31:30 +02:00
rocket.h
synclink_gt.c	tty: synclink_gt: Adjust indentation in several functions	2020-02-24 08:34:47 +01:00
synclink.c
synclinkmp.c	tty: synclinkmp: Adjust indentation in several functions	2020-02-24 08:34:47 +01:00
sysrq.c	sysrq: Remove duplicated sysrq message	2020-03-05 16:42:15 +01:00
tty_audit.c
tty_baudrate.c
tty_buffer.c
tty_io.c
tty_ioctl.c
tty_jobctrl.c
tty_ldisc.c	tty: Don't block on IO when ldisc change is pending	2019-12-13 08:52:28 +01:00
tty_ldsem.c
tty_mutex.c
tty_port.c	serdev: ttyport: restore client ops on deregistration	2020-02-28 16:38:49 +01:00
vcc.c	sparc64: vcc: Fix error return code in vcc_probe()	2020-10-01 13:14:43 +02:00