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authorPeter Hurley <peter@hurleysoftware.com>2015-01-19 13:05:03 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-06 14:43:30 -0800
commit2ebef5a86218588cf8e85c3df27804453366012c (patch)
tree0327d54f55c0605fa3b61f16c19b33be6e86567e
parent420593bb506126a92935d5a350cad7dfac8fa982 (diff)
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tty: Prevent untrappable signals from malicious program
commit 37480a05685ed5b8e1b9bf5e5c53b5810258b149 upstream. 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@mit.edu> Cc: Howard Chu <hyc@symas.com> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/pty.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 25c9bc783722..e49616eeb1cc 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -209,6 +209,9 @@ static int pty_signal(struct tty_struct *tty, int sig)
unsigned long flags;
struct pid *pgrp;
+ if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
+ return -EINVAL;
+
if (tty->link) {
spin_lock_irqsave(&tty->link->ctrl_lock, flags);
pgrp = get_pid(tty->link->pgrp);