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authorDmitry Vyukov <dvyukov@google.com>2015-09-17 17:17:08 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-04 19:03:40 +0100
commit7098296a362a96051fa120abf48f0095818b99cd (patch)
treed5faab1ed808c7fc3d55be88d431452b43e1e63e
parente81107d4c6bd098878af9796b24edc8d4a9524fd (diff)
tty: fix data race in flush_to_ldisc
flush_to_ldisc reads port->itty and checks that it is not NULL, concurrently release_tty sets port->itty to NULL. It is possible that flush_to_ldisc loads port->itty once, ensures that it is not NULL, but then reloads it again and uses. The second load can already return NULL, which will cause a crash. Use READ_ONCE to read port->itty. The data race was found with KernelThreadSanitizer (KTSAN). Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/tty_buffer.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 5a3fa8913880..23de97de09a4 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -467,7 +467,7 @@ static void flush_to_ldisc(struct work_struct *work)
struct tty_struct *tty;
struct tty_ldisc *disc;
- tty = port->itty;
+ tty = READ_ONCE(port->itty);
if (tty == NULL)
return;