On 3/28/2019 10:40 PM, Colin King wrote:
From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
The return from tty_write_room could potentially be negative if
a tty write_room driver returns an error number (not that any seem
to do). Rather than just check for a zero return, also check for
a -ve return. This avoids the unsigned nr being set to a large unsigned
value on the assignment from variable space and can lead to overflowing
the buffer buf. Better to be safe than assume all write_room
implementations in tty drivers are going to do the right thing.
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Looks reasonable to me.
Reviewed-by: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
-Mukesh.
---
drivers/tty/n_tty.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 9cdb0fa3c4bf..66630787fbf9 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -550,7 +550,7 @@ static ssize_t process_output_block(struct tty_struct *tty,
mutex_lock(&ldata->output_lock);
space = tty_write_room(tty);
- if (!space) {
+ if (space <= 0) {
mutex_unlock(&ldata->output_lock);
return 0;
}
