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| author | Colin Ian King <colin.king@canonical.com> | 2019-03-30 00:46:28 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-16 15:21:33 +0200 |
| commit | 9ef8927f45f2f8e365cda7cda81c079f29b8ad74 (patch) | |
| tree | 0a189703d0d9d0e686a6d30a1789792ffe80d1c4 | |
| parent | f16aa97d3f575ea660f49d4698efe1c4a4c60919 (diff) | |
| download | linux-9ef8927f45f2f8e365cda7cda81c079f29b8ad74.tar.gz | |
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>
| -rw-r--r-- | drivers/tty/n_tty.c | 4 |
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; |