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pcmcia: synclink_cs: fix potential tty NULL dereference 

tty_port_tty_get() can return NULL after port hangup that may happen anytime.
The patch adds checks that tty_port_tty_get() returns nonNULL around places
where tty is actually used.

I have no actual hardware to test the patch, so I have updated rx side
processing from common sense only.

v2: rx handling updated according Alan Cox feedback.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexey Khoroshilov 2012-09-15 01:29:37 +04:00 committed by Greg Kroah-Hartman
parent 08b79dd10b
commit 221b7b5796
1 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/char/pcmcia/synclink_cs.c
View File

@ -891,6 +891,14 @@ static void rx_ready_async(MGSLPC_INFO *info, int tcd, struct tty_struct *tty)
int work = 0;
struct mgsl_icount *icount = &info->icount;
if (!tty) {
/* tty is not available anymore */
issue_command(info, CHA, CMD_RXRESET);
if (debug_level >= DEBUG_LEVEL_ISR)
printk("%s(%d):rx_ready_async(tty=NULL)\n",__FILE__,__LINE__);
return;
}
if (tcd) {
/* early termination, get FIFO count from RBCL register */
fifo_count = (unsigned char)(read_reg(info, CHA+RBCL) & 0x1f);
@ -980,7 +988,7 @@ static void tx_done(MGSLPC_INFO *info, struct tty_struct *tty)
else
#endif
{
if (tty->stopped || tty->hw_stopped) {
if (tty && (tty->stopped || tty->hw_stopped)) {
tx_stop(info);
return;
}
@ -1000,7 +1008,7 @@ static void tx_ready(MGSLPC_INFO *info, struct tty_struct *tty)
if (!info->tx_active)
return;
} else {
if (tty->stopped || tty->hw_stopped) {
if (tty && (tty->stopped || tty->hw_stopped)) {
tx_stop(info);
return;
}
@ -1050,13 +1058,12 @@ static void cts_change(MGSLPC_INFO *info, struct tty_struct *tty)
wake_up_interruptible(&info->status_event_wait_q);
wake_up_interruptible(&info->event_wait_q);
if (info->port.flags & ASYNC_CTS_FLOW) {
if (tty && (info->port.flags & ASYNC_CTS_FLOW)) {
if (tty->hw_stopped) {
if (info->serial_signals & SerialSignal_CTS) {
if (debug_level >= DEBUG_LEVEL_ISR)
printk("CTS tx start...");
if (tty)
tty->hw_stopped = 0;
tty->hw_stopped = 0;
tx_start(info, tty);
info->pending_bh |= BH_TRANSMIT;
return;
@ -1065,8 +1072,7 @@ static void cts_change(MGSLPC_INFO *info, struct tty_struct *tty)
if (!(info->serial_signals & SerialSignal_CTS)) {
if (debug_level >= DEBUG_LEVEL_ISR)
printk("CTS tx stop...");
if (tty)
tty->hw_stopped = 1;
tty->hw_stopped = 1;
tx_stop(info);
}
}