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authorColin Ian King <colin.king@canonical.com>2019-03-30 03:46:28 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-16 16:21:33 +0300
commit9ef8927f45f2f8e365cda7cda81c079f29b8ad74 (patch)
tree0a189703d0d9d0e686a6d30a1789792ffe80d1c4 /drivers/tty/n_tty.c
parentf16aa97d3f575ea660f49d4698efe1c4a4c60919 (diff)
downloadlinux-9ef8927f45f2f8e365cda7cda81c079f29b8ad74.tar.xz
n_tty: check for negative and zero space return from tty_write_room
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@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 9cdb0fa3c4bf..f9c584244f72 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -550,9 +550,9 @@ 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;
+ return space;
}
if (nr > space)
nr = space;