| Message ID | 1363217434-29262-1-git-send-email-jslaby@suse.cz |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
From: Jiri Slaby <jslaby@suse.cz> Date: Thu, 14 Mar 2013 00:30:34 +0100 > The following commits: > * 6732c8bb8671acbdac6cdc93dd72ddd581dd5e25 (TTY: switch > tty_schedule_flip) > * 2e124b4a390ca85325fae75764bef92f0547fa25 (TTY: switch > tty_flip_buffer_push) > * 05c7cd39907184328f48d3e7899f9cdd653ad336 (TTY: switch > tty_insert_flip_string) > * 92a19f9cec9a80ad93c06e115822deb729e2c6ad (TTY: switch > tty_insert_flip_char) > * 227434f8986c3827a1faedd1feb437acd6285315 (TTY: switch > tty_buffer_request_room to tty_port) > > introduced a potential NULL dereference to some drivers. In > particular, when the device is used as a console, incoming bytes can > kill the box. This is caused by removed checks for TTY against NULL. > > It happened because it was unclear to me why the checks were there. I > assumed them superfluous because the interrupts were unbound or > otherwise stopped. But this is not the case for consoles for these > drivers, as was pointed out by David Miller. > > Now, this patch re-introduces the checks (at this point we check > port->state, not the tty proper, as we do not care about tty pointers > anymore). For both of the drivers, we place the check below the > handling of break signal so that sysrq can actually work. (One needs > to issue a break and then sysrq key within the following 5 seconds.) > > We do not change sc26xx, sunhv, and sunsu here because they behave the > same as before. People having that hardware should fix the driver > eventually, however. They always could unconditionally dereference tty > in receive_chars, port->state in uart_handle_dcd_change, and > up->port.state->port.tty. > > There is perhaps more to fix in all those drivers, but they are at > least in a state they were before. > > Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: David S. Miller <davem@davemloft.net> -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c index 8de2213..a422c8b 100644 --- a/drivers/tty/serial/sunsab.c +++ b/drivers/tty/serial/sunsab.c @@ -203,7 +203,7 @@ receive_chars(struct uart_sunsab_port *up, flag = TTY_FRAME; } - if (uart_handle_sysrq_char(&up->port, ch)) + if (uart_handle_sysrq_char(&up->port, ch) || !port) continue; if ((stat->sreg.isr0 & (up->port.ignore_status_mask & 0xff)) == 0 && diff --git a/drivers/tty/serial/sunzilog.c b/drivers/tty/serial/sunzilog.c index 27669ff..813ef8e 100644 --- a/drivers/tty/serial/sunzilog.c +++ b/drivers/tty/serial/sunzilog.c @@ -388,7 +388,7 @@ sunzilog_receive_chars(struct uart_sunzilog_port *up, else if (r1 & CRC_ERR) flag = TTY_FRAME; } - if (uart_handle_sysrq_char(&up->port, ch)) + if (uart_handle_sysrq_char(&up->port, ch) || !port) continue; if (up->port.ignore_status_mask == 0xff ||
The following commits: * 6732c8bb8671acbdac6cdc93dd72ddd581dd5e25 (TTY: switch tty_schedule_flip) * 2e124b4a390ca85325fae75764bef92f0547fa25 (TTY: switch tty_flip_buffer_push) * 05c7cd39907184328f48d3e7899f9cdd653ad336 (TTY: switch tty_insert_flip_string) * 92a19f9cec9a80ad93c06e115822deb729e2c6ad (TTY: switch tty_insert_flip_char) * 227434f8986c3827a1faedd1feb437acd6285315 (TTY: switch tty_buffer_request_room to tty_port) introduced a potential NULL dereference to some drivers. In particular, when the device is used as a console, incoming bytes can kill the box. This is caused by removed checks for TTY against NULL. It happened because it was unclear to me why the checks were there. I assumed them superfluous because the interrupts were unbound or otherwise stopped. But this is not the case for consoles for these drivers, as was pointed out by David Miller. Now, this patch re-introduces the checks (at this point we check port->state, not the tty proper, as we do not care about tty pointers anymore). For both of the drivers, we place the check below the handling of break signal so that sysrq can actually work. (One needs to issue a break and then sysrq key within the following 5 seconds.) We do not change sc26xx, sunhv, and sunsu here because they behave the same as before. People having that hardware should fix the driver eventually, however. They always could unconditionally dereference tty in receive_chars, port->state in uart_handle_dcd_change, and up->port.state->port.tty. There is perhaps more to fix in all those drivers, but they are at least in a state they were before. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: "David S. Miller" <davem@davemloft.net> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Rob Herring <rob.herring@calxeda.com> Cc: sparclinux@vger.kernel.org --- drivers/tty/serial/sunsab.c | 2 +- drivers/tty/serial/sunzilog.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)