Peter Hurley 62a0d8d7c2 tty: Fix lockless tty buffer race ... Commit 6a20dbd6ca, "tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc" correctly identifies an unsafe race condition between __tty_buffer_request_room() and flush_to_ldisc(), where the consumer flush_to_ldisc() prematurely advances the head before consuming the last of the data committed. For example: CPU 0 | CPU 1 __tty_buffer_request_room | flush_to_ldisc ... | ... | count = head->commit - head->read n = tty_buffer_alloc() | b->commit = b->used | b->next = n | | if (!count) /* T */ | if (head->next == NULL) /* F */ | buf->head = head->next In this case, buf->head has been advanced but head->commit may have been updated with a new value. Instead of reintroducing an unnecessary lock, fix the race locklessly. Read the commit-next pair in the reverse order of writing, which guarantees the commit value read is the latest value written if the head is advancing. Reported-by: Manfred Schlaegl <manfred.schlaegl@gmx.at> Cc: <stable@vger.kernel.org> # 3.12.x+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2014-05-03 18:14:28 -04:00
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hvc	drivers/tty/hvc: don't free hvc_console_setup after init	2014-05-03 18:14:28 -04:00
ipwireless	…
serial	tty: serial: 8250_core.c Bug fix for Exar chips.	2014-05-03 18:13:05 -04:00
vt	…
Kconfig	…
Makefile	…
amiserial.c	…
bfin_jtag_comm.c	…
cyclades.c	…
ehv_bytechan.c	…
goldfish.c	…
isicom.c	…
metag_da.c	…
moxa.c	…
moxa.h	…
mxser.c	…
mxser.h	…
n_gsm.c	…
n_hdlc.c	…
n_r3964.c	…
n_tracerouter.c	…
n_tracesink.c	…
n_tracesink.h	…
n_tty.c	n_tty: Fix n_tty_write crash when echoing in raw mode	2014-05-03 18:13:05 -04:00
nozomi.c	…
pty.c	…
rocket.c	…
rocket.h	…
rocket_int.h	…
synclink.c	…
synclink_gt.c	…
synclinkmp.c	…
sysrq.c	…
tty_audit.c	…
tty_buffer.c	tty: Fix lockless tty buffer race	2014-05-03 18:14:28 -04:00
tty_io.c	tty: fix memleak in alloc_pid	2014-04-16 14:31:13 -07:00
tty_ioctl.c	…
tty_ldisc.c	…
tty_ldsem.c	…
tty_mutex.c	…
tty_port.c	…