Commit 26df6d13406d1a5 ("tty: Add EXTPROC support for LINEMODE")
allows a process which has opened a pty master to send _any_ signal
to the process group of the pty slave. Although potentially
exploitable by a malicious program running a setuid program on
a pty slave, it's unknown if this exploit currently exists.
Limit to signals actually used.
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Howard Chu <hyc@xxxxxxxxx>
Cc: One Thousand Gnomes <gnomes@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 2.6.36+
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
v2: Fixed stupidity.
drivers/tty/pty.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index a9d256d..6e1f150 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -210,6 +210,9 @@ static int pty_signal(struct tty_struct *tty, int sig)
{
struct pid *pgrp;
+ if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
+ return -EINVAL;
+
if (tty->link) {
pgrp = tty_get_pgrp(tty->link);
if (pgrp)
--
2.2.2
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