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pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

PATCH New Eric Biggers 4 participants 6 messages May 13, 2018 – Jun 5, 2018

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Eric Biggers

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#0 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

From: Eric Biggers <[email protected]>

Test for a bug in the kernel's tty layer where an infinite loop could occur if the EXTPROC and ICANON terminal modes were combined. This bug was found by the syzkaller fuzzer and was fixed in v4.15.

Signed-off-by Eric Biggers <[email protected]>
---
 runtest/pty                     |  1 +
 testcases/kernel/pty/.gitignore |  1 +
 testcases/kernel/pty/pty02.c    | 58 +++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 testcases/kernel/pty/pty02.c
runtest/pty +1 -0
index 92c89ab31..52e2c07f1 100644
@@ -1,5 +1,6 @@
 #DESCRIPTION:Terminal type stress
 pty01 pty01
+pty02 pty02
 ptem01 ptem01
 hangup01 hangup01
testcases/kernel/pty/.gitignore +1 -0
index db16401dc..131b8a077 100644
@@ -1,3 +1,4 @@
 /hangup01
 /ptem01
 /pty01
+/pty02
testcases/kernel/pty/pty02.c new file +58 -0

58 lines not on this page · raw message

Signature · 1 line
2.17.0
#1 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

Hi!

testcases/kernel/pty/pty02.c line 52

Quoted 2 lines
testcases/kernel/pty/pty02.c new file +2 -0
+	tst_res(TINFO, "Calling FIONREAD, this will hang in n_tty_ioctl() if the bug is present...");
+	SAFE_IOCTL(pts, FIONREAD, &nbytes);

I've added two SAFE_CLOSE() here so that the test works with the -i 1000 as well and pushed, thanks.

Quoted 2 lines
testcases/kernel/pty/pty02.c new file +2 -0
+	tst_res(TPASS, "Got to the end without hanging");
+}
Signature · 2 lines
Cyril Hrubis
[email protected]
#2 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

In reply to Eric Biggers

----- Original Message -----

Quoted 9 lines

+ * Regression test for commit 966031f340185 ("n_tty: fix EXTPROC vs ICANON
+ * interaction with TIOCINQ (aka FIONREAD)"). The test reproduces a hang
+ * (infinite loop in the kernel) after a pseudoterminal is put in both canonical
+ * (ICANON) and external processing (EXTPROC) mode, some data is written to the
+ * master and read from the slave, and the FIONREAD ioctl is called on the
+ * slave. This is simplified from a syzkaller-generated reproducer.
+ */

testcases/kernel/pty/pty02.c line 34

Quoted 9 lines
testcases/kernel/pty/pty02.c new file +9 -0
+
+#include <stdlib.h>
+#include <termio.h>
+
+#include "tst_test.h"
+
+static void do_test(void)
+{
+	struct termios io = { .c_lflag = EXTPROC | ICANON };

Hi,

I'm running into compilation errors on older distros (RHEL5/6) with this test:

pty02.c: In function ‘do_test’:
pty02.c:34: error: ‘EXTPROC’ undeclared (first use in this function) pty02.c:34: error: (Each undeclared identifier is reported only once pty02.c:34: error: for each function it appears in.)
make: *** [pty02] Error 1

We should probably ifdef the test, because adding define to LAPI still makes it fail:

tst_test.c:1015: INFO: Timeout per run is 0h 05m 00s pty02.c:44: BROK: tcsetattr() failed: EINVAL

Regards,
Jan

#3 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

Hi Jan,

Quoted 31 lines · Jan Stancek

----- Original Message -----

Quoted 1 line

+ * Regression test for commit 966031f340185 ("n_tty: fix EXTPROC vs

ICANON

Quoted 1 line

+ * interaction with TIOCINQ (aka FIONREAD)"). The test reproduces a

hang

Quoted 3 lines

+ * (infinite loop in the kernel) after a pseudoterminal is put in both canonical
+ * (ICANON) and external processing (EXTPROC) mode, some data is

written to

Quoted 2 lines

the
+ * master and read from the slave, and the FIONREAD ioctl is called on

the

testcases/kernel/pty/pty02.c line 34

Quoted 11 lines

+ * slave. This is simplified from a syzkaller-generated reproducer.
+ */

testcases/kernel/pty/pty02.c new file +9 -0
+
+#include <stdlib.h>
+#include <termio.h>
+
+#include "tst_test.h"
+
+static void do_test(void)
+{
+     struct termios io = { .c_lflag = EXTPROC | ICANON };

Hi,

I'm running into compilation errors on older distros (RHEL5/6) with this test:

Quoted 9 lines

pty02.c: In function ‘do_test’:
pty02.c:34: error: ‘EXTPROC’ undeclared (first use in this function) pty02.c:34: error: (Each undeclared identifier is reported only once pty02.c:34: error: for each function it appears in.)
make: *** [pty02] Error 1

We should probably ifdef the test, because adding define to LAPI still makes it fail:

​Xiao and I have also noticed this, ​beside the undefine issue, there are still
other problems in pty02 test.

The discuss is here:
http://lists.linux.it/pipermail/ltp/2018-May/008253.html

Quoted 10 lines

tst_test.c:1015: INFO: Timeout per run is 0h 05m 00s pty02.c:44: BROK: tcsetattr() failed: EINVAL

Regards,
Jan

--
Mailing list info: https://lists.linux.it/listinfo/ltp

Signature · 5 lines
Regards,
Li Wang
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#4 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

In reply to Jan Stancek

Hi!

Quoted 9 lines

I'm running into compilation errors on older distros (RHEL5/6) with this test:

pty02.c: In function ???do_test???:
pty02.c:34: error: ???EXTPROC??? undeclared (first use in this function) pty02.c:34: error: (Each undeclared identifier is reported only once pty02.c:34: error: for each function it appears in.)
make: *** [pty02] Error 1

Quoted 5 lines

We should probably ifdef the test, because adding define to LAPI still makes it fail:

tst_test.c:1015: INFO: Timeout per run is 0h 05m 00s pty02.c:44: BROK: tcsetattr() failed: EINVAL

Or we can return TCONF on EINVAL since EINVAL means unsupported value anyway...

Signature · 2 lines
Cyril Hrubis
[email protected]
#5 lore raw

PATCH 1/1 pty/pty02: new test for hang involving EXTPROC|ICANON terminal mode

Quoted 10 lines · Cyril Hrubis

Hi!

Quoted 9 lines

I'm running into compilation errors on older distros (RHEL5/6) with this test:

pty02.c: In function ???do_test???:
pty02.c:34: error: ???EXTPROC??? undeclared (first use in this function) pty02.c:34: error: (Each undeclared identifier is reported only once pty02.c:34: error: for each function it appears in.)
make: *** [pty02] Error 1

Quoted 9 lines
Quoted 5 lines

We should probably ifdef the test, because adding define to LAPI still makes it fail:

tst_test.c:1015: INFO: Timeout per run is 0h 05m 00s pty02.c:44: BROK: tcsetattr() failed: EINVAL

Or we can return TCONF on EINVAL since EINVAL means unsupported value anyway...

​Maybe at least we should do more try before skipping it when getting EINVAL. Because sometimes it also fails with EINVAL when using a termios structure that was not obtained using tcgeaatr(). tcsetattr() should use only a termios structure that was obtained by tcgetattr().

pty02.c works fine on mainline kernel-v4.17 after applying this:
http://lists.linux.it/pipermail/ltp/2018-May/008253.html

What do you think?

Signature · 5 lines
Regards,
Li Wang
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