On 11/6/24 3:58 AM, Qiu-ji Chen wrote:
Our static checker found a bug where set_serial_info() uses a mutex, but
get_serial_info() does not. Fortunately, the impact of this is relatively
minor. It doesn't cause a crash or any other serious issues. However, if a
race condition occurs between set_serial_info() and get_serial_info(),
there is a chance that the data returned by get_serial_info() will be
meaningless.
Signed-off-by: Qiu-ji Chen <chenqiuji666@xxxxxxxxx>
Fixes: 0aad5ad563c8 ("greybus/uart: switch to ->[sg]et_serial()")
Looks good.
Reviewed-by: Alex Elder <elder@xxxxxxxxxxxx>
PS I was going to suggest computing the close delay and closing wait
outside the mutex, as get_serial_info() above it does. But it's
minor and there's no reason to hold up your patch for that.
---
V2:
Modified the patch description to make it more concise and easier to understand.
Changed the fix code to ensure the logic is correct.
Thanks to Johan Hovold and Dan Carpenter for helpful suggestion.
---
drivers/staging/greybus/uart.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index cdf4ebb93b10..8eab94cb06fa 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -596,11 +596,13 @@ static int get_serial_info(struct tty_struct *tty,
struct gb_tty *gb_tty = tty->driver_data;
ss->line = gb_tty->minor;
+ mutex_lock(&gb_tty->port.mutex);
ss->close_delay = jiffies_to_msecs(gb_tty->port.close_delay) / 10;
ss->closing_wait =
gb_tty->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
ASYNC_CLOSING_WAIT_NONE :
jiffies_to_msecs(gb_tty->port.closing_wait) / 10;
+ mutex_unlock(&gb_tty->port.mutex);
return 0;
}
