memory leak in pty_common_install

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 6789f873 Merge tag 'pm-5.3-rc2' of git://git.kernel.org/pu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1696897c600000
kernel config: https://syzkaller.appspot.com/x/.config?x=339b6a6b3640d115
dashboard link: https://syzkaller.appspot.com/bug?extid=bdebcbf44250d75bdd82
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=153d7544600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bdebcb...@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff88810d84d400 (size 512):
comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
hex dump (first 32 bytes):
50 d4 84 0d 81 88 ff ff e0 ff ff ff 0f 00 00 00 P...............
10 d4 84 0d 81 88 ff ff 10 d4 84 0d 81 88 ff ff ................
backtrace:
[<000000003d61da44>] kmemleak_alloc_recursive
include/linux/kmemleak.h:43 [inline]
[<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
[<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
[<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
[<00000000a6239e0a>] kmalloc include/linux/slab.h:552 [inline]
[<00000000a6239e0a>] pty_common_install+0x4e/0x2b0 drivers/tty/pty.c:391
[<00000000bd8cb19d>] pty_unix98_install+0x20/0x30 drivers/tty/pty.c:740
[<000000001b46b5e1>] tty_driver_install_tty drivers/tty/tty_io.c:1227
[inline]
[<000000001b46b5e1>] tty_init_dev drivers/tty/tty_io.c:1340 [inline]
[<000000001b46b5e1>] tty_init_dev+0x86/0x210 drivers/tty/tty_io.c:1317
[<00000000845ae712>] ptmx_open drivers/tty/pty.c:845 [inline]
[<00000000845ae712>] ptmx_open+0xba/0x1c0 drivers/tty/pty.c:811
[<000000007e87d771>] chrdev_open+0xe3/0x290 fs/char_dev.c:414
[<00000000bd556826>] do_dentry_open+0x199/0x4f0 fs/open.c:797
[<000000001ba9145b>] vfs_open+0x35/0x40 fs/open.c:906
[<00000000c0275eb4>] do_last fs/namei.c:3416 [inline]
[<00000000c0275eb4>] path_openat+0x854/0x1cd0 fs/namei.c:3533
[<00000000156ad8b1>] do_filp_open+0xaa/0x130 fs/namei.c:3563
[<00000000074d96c0>] do_sys_open+0x253/0x330 fs/open.c:1089
[<000000009f7fc64a>] __do_sys_openat fs/open.c:1116 [inline]
[<000000009f7fc64a>] __se_sys_openat fs/open.c:1110 [inline]
[<000000009f7fc64a>] __x64_sys_openat+0x24/0x30 fs/open.c:1110
[<000000005ca4479f>] do_syscall_64+0x76/0x1a0
arch/x86/entry/common.c:296
[<00000000e1f64b0f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff88810e639800 (size 1024):
comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
hex dump (first 32 bytes):
01 54 00 00 01 00 00 00 00 00 00 00 00 00 00 00 .T..............
00 83 fa 19 82 88 ff ff a0 7f 9b 83 ff ff ff ff ................
backtrace:
[<000000003d61da44>] kmemleak_alloc_recursive
include/linux/kmemleak.h:43 [inline]
[<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
[<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
[<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
[<000000001cfffc30>] kmalloc include/linux/slab.h:552 [inline]
[<000000001cfffc30>] kzalloc include/linux/slab.h:748 [inline]
[<000000001cfffc30>] alloc_tty_struct+0x3f/0x290
drivers/tty/tty_io.c:2981
[<000000001946a70c>] pty_common_install+0xac/0x2b0 drivers/tty/pty.c:399
[<00000000bd8cb19d>] pty_unix98_install+0x20/0x30 drivers/tty/pty.c:740
[<000000001b46b5e1>] tty_driver_install_tty drivers/tty/tty_io.c:1227
[inline]
[<000000001b46b5e1>] tty_init_dev drivers/tty/tty_io.c:1340 [inline]
[<000000001b46b5e1>] tty_init_dev+0x86/0x210 drivers/tty/tty_io.c:1317
[<00000000845ae712>] ptmx_open drivers/tty/pty.c:845 [inline]
[<00000000845ae712>] ptmx_open+0xba/0x1c0 drivers/tty/pty.c:811
[<000000007e87d771>] chrdev_open+0xe3/0x290 fs/char_dev.c:414
[<00000000bd556826>] do_dentry_open+0x199/0x4f0 fs/open.c:797
[<000000001ba9145b>] vfs_open+0x35/0x40 fs/open.c:906
[<00000000c0275eb4>] do_last fs/namei.c:3416 [inline]
[<00000000c0275eb4>] path_openat+0x854/0x1cd0 fs/namei.c:3533
[<00000000156ad8b1>] do_filp_open+0xaa/0x130 fs/namei.c:3563
[<00000000074d96c0>] do_sys_open+0x253/0x330 fs/open.c:1089
[<000000009f7fc64a>] __do_sys_openat fs/open.c:1116 [inline]
[<000000009f7fc64a>] __se_sys_openat fs/open.c:1110 [inline]
[<000000009f7fc64a>] __x64_sys_openat+0x24/0x30 fs/open.c:1110
[<000000005ca4479f>] do_syscall_64+0x76/0x1a0
arch/x86/entry/common.c:296
[<00000000e1f64b0f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot can test patches for this bug, for details see:
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[Jiri Slaby]

So this is tty_port for o_tty.

...

> BUG: memory leak
> unreferenced object 0xffff88810e639800 (size 1024):
>   comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
>   hex dump (first 32 bytes):
>     01 54 00 00 01 00 00 00 00 00 00 00 00 00 00 00  .T..............
>     00 83 fa 19 82 88 ff ff a0 7f 9b 83 ff ff ff ff  ................
>   backtrace:
>     [<000000003d61da44>] kmemleak_alloc_recursive
> include/linux/kmemleak.h:43 [inline]
>     [<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
>     [<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
>     [<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
>     [<000000001cfffc30>] kmalloc include/linux/slab.h:552 [inline]
>     [<000000001cfffc30>] kzalloc include/linux/slab.h:748 [inline]
>     [<000000001cfffc30>] alloc_tty_struct+0x3f/0x290
> drivers/tty/tty_io.c:2981
>     [<000000001946a70c>] pty_common_install+0xac/0x2b0
> drivers/tty/pty.c:399

And this is o_tty proper. So we leak whole o_tty under some
circumstances... Trying to reproduce.

BTW the reproducer says:
ioctl$TCSETS(r0, 0x40045431, ...)

But 0x40045431 is TIOCSPTLCK, not TCSETS.

thanks,
--
js
suse labs

[Jiri Slaby]

>> BUG: memory leakx

>> unreferenced object 0xffff88810e639800 (size 1024):
>>   comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
>>   hex dump (first 32 bytes):
>>     01 54 00 00 01 00 00 00 00 00 00 00 00 00 00 00  .T..............
>>     00 83 fa 19 82 88 ff ff a0 7f 9b 83 ff ff ff ff  ................
>>   backtrace:
>>     [<000000003d61da44>] kmemleak_alloc_recursive
>> include/linux/kmemleak.h:43 [inline]
>>     [<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
>>     [<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
>>     [<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
>>     [<000000001cfffc30>] kmalloc include/linux/slab.h:552 [inline]
>>     [<000000001cfffc30>] kzalloc include/linux/slab.h:748 [inline]
>>     [<000000001cfffc30>] alloc_tty_struct+0x3f/0x290
>> drivers/tty/tty_io.c:2981
>>     [<000000001946a70c>] pty_common_install+0xac/0x2b0
>> drivers/tty/pty.c:399
>
> And this is o_tty proper. So we leak whole o_tty under some
> circumstances... Trying to reproduce.

And I failed.

Looking into the code, I also can't find the scenario. One virtually
possible could be hangup_work being cancelled while release_one_tty was
scheduled on it. But I see this nowhere.

A C reproducer would help.

[Hillf Danton]

On Tue, 30 Jul 2019 08:08:05 -0700

> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 6789f873 Merge tag 'pm-5.3-rc2' of git://git.kernel.org/pu..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1696897c600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=339b6a6b3640d115
> dashboard link: https://syzkaller.appspot.com/bug?extid=bdebcbf44250d75bdd82
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=153d7544600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+bdebcb...@syzkaller.appspotmail.com
>
> BUG: memory leak
> unreferenced object 0xffff88810d84d400 (size 512):
> comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
> hex dump (first 32 bytes):
> 50 d4 84 0d 81 88 ff ff e0 ff ff ff 0f 00 00 00 P...............
> 10 d4 84 0d 81 88 ff ff 10 d4 84 0d 81 88 ff ff ................
> backtrace:
> [<000000003d61da44>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
> [<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
> [<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
> [<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
> [<00000000a6239e0a>] kmalloc include/linux/slab.h:552 [inline]
> [<00000000a6239e0a>] pty_common_install+0x4e/0x2b0 drivers/tty/pty.c:391

> [<00000000bd8cb19d>] pty_unix98_install+0x20/0x30 drivers/tty/pty.c:740
> [<000000001b46b5e1>] tty_driver_install_tty drivers/tty/tty_io.c:1227 [inline]
> [<000000001b46b5e1>] tty_init_dev drivers/tty/tty_io.c:1340 [inline]
> [<000000001b46b5e1>] tty_init_dev+0x86/0x210 drivers/tty/tty_io.c:1317
> [<00000000845ae712>] ptmx_open drivers/tty/pty.c:845 [inline]
> [<00000000845ae712>] ptmx_open+0xba/0x1c0 drivers/tty/pty.c:811
> [<000000007e87d771>] chrdev_open+0xe3/0x290 fs/char_dev.c:414
> [<00000000bd556826>] do_dentry_open+0x199/0x4f0 fs/open.c:797
> [<000000001ba9145b>] vfs_open+0x35/0x40 fs/open.c:906
> [<00000000c0275eb4>] do_last fs/namei.c:3416 [inline]
> [<00000000c0275eb4>] path_openat+0x854/0x1cd0 fs/namei.c:3533
> [<00000000156ad8b1>] do_filp_open+0xaa/0x130 fs/namei.c:3563
> [<00000000074d96c0>] do_sys_open+0x253/0x330 fs/open.c:1089
> [<000000009f7fc64a>] __do_sys_openat fs/open.c:1116 [inline]
> [<000000009f7fc64a>] __se_sys_openat fs/open.c:1110 [inline]
> [<000000009f7fc64a>] __x64_sys_openat+0x24/0x30 fs/open.c:1110
> [<000000005ca4479f>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:296
> [<00000000e1f64b0f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>

> BUG: memory leak

> unreferenced object 0xffff88810e639800 (size 1024):
> comm "syz-executor.5", pid 7522, jiffies 4294954305 (age 14.260s)
> hex dump (first 32 bytes):
> 01 54 00 00 01 00 00 00 00 00 00 00 00 00 00 00 .T..............
> 00 83 fa 19 82 88 ff ff a0 7f 9b 83 ff ff ff ff ................
> backtrace:
> [<000000003d61da44>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
> [<000000003d61da44>] slab_post_alloc_hook mm/slab.h:522 [inline]
> [<000000003d61da44>] slab_alloc mm/slab.c:3319 [inline]
> [<000000003d61da44>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
> [<000000001cfffc30>] kmalloc include/linux/slab.h:552 [inline]
> [<000000001cfffc30>] kzalloc include/linux/slab.h:748 [inline]
> [<000000001cfffc30>] alloc_tty_struct+0x3f/0x290 drivers/tty/tty_io.c:2981
> [<000000001946a70c>] pty_common_install+0xac/0x2b0 drivers/tty/pty.c:399

> [<00000000bd8cb19d>] pty_unix98_install+0x20/0x30 drivers/tty/pty.c:740
> [<000000001b46b5e1>] tty_driver_install_tty drivers/tty/tty_io.c:1227 [inline]
> [<000000001b46b5e1>] tty_init_dev drivers/tty/tty_io.c:1340 [inline]
> [<000000001b46b5e1>] tty_init_dev+0x86/0x210 drivers/tty/tty_io.c:1317
> [<00000000845ae712>] ptmx_open drivers/tty/pty.c:845 [inline]
> [<00000000845ae712>] ptmx_open+0xba/0x1c0 drivers/tty/pty.c:811
> [<000000007e87d771>] chrdev_open+0xe3/0x290 fs/char_dev.c:414
> [<00000000bd556826>] do_dentry_open+0x199/0x4f0 fs/open.c:797
> [<000000001ba9145b>] vfs_open+0x35/0x40 fs/open.c:906
> [<00000000c0275eb4>] do_last fs/namei.c:3416 [inline]
> [<00000000c0275eb4>] path_openat+0x854/0x1cd0 fs/namei.c:3533
> [<00000000156ad8b1>] do_filp_open+0xaa/0x130 fs/namei.c:3563
> [<00000000074d96c0>] do_sys_open+0x253/0x330 fs/open.c:1089
> [<000000009f7fc64a>] __do_sys_openat fs/open.c:1116 [inline]
> [<000000009f7fc64a>] __se_sys_openat fs/open.c:1110 [inline]
> [<000000009f7fc64a>] __x64_sys_openat+0x24/0x30 fs/open.c:1110
> [<000000005ca4479f>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:296
> [<00000000e1f64b0f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reset tty for port if none cares the open result.

--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -669,6 +669,8 @@ EXPORT_SYMBOL_GPL(tty_port_install);
int tty_port_open(struct tty_port *port, struct tty_struct *tty,
struct file *filp)
{
+ int retval = 0;
+
spin_lock_irq(&port->lock);
++port->count;
spin_unlock_irq(&port->lock);
@@ -685,16 +687,18 @@ int tty_port_open(struct tty_port *port,
if (!tty_port_initialized(port)) {
clear_bit(TTY_IO_ERROR, &tty->flags);
if (port->ops->activate) {
- int retval = port->ops->activate(port, tty);
- if (retval) {
- mutex_unlock(&port->mutex);
- return retval;
- }
+ retval = port->ops->activate(port, tty);
+ if (retval)
+ goto out;
}
tty_port_set_initialized(port, 1);
}
+out:
mutex_unlock(&port->mutex);
- return tty_port_block_til_ready(port, tty, filp);
+ if (!retval)
+ retval = tty_port_block_til_ready(port, tty, filp);
+ if (retval)
+ tty_port_tty_set(port, 0);
+ return retval;
}
-
EXPORT_SYMBOL(tty_port_open);
--

[Jiri Slaby]

Could you elaborate on how tty_port_open affects ptys? I.e. how does
this report relates to the change below?

And why do you think it is necessary at all? tty_port_close should take
care of it.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d9b2ba67917c Merge tag 'platform-drivers-x86-v5.19-3' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1795f0f0080000
kernel config: https://syzkaller.appspot.com/x/.config?x=b6c1840347c4c391
dashboard link: https://syzkaller.appspot.com/bug?extid=bdebcbf44250d75bdd82
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13d01f90080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=126f34f0080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bdebcb...@syzkaller.appspotmail.com

Warning: Permanently added '10.128.1.122' (ECDSA) to the list of known hosts.
executing program
executing program
executing program
BUG: memory leak
unreferenced object 0xffff88810222e600 (size 512):
comm "syz-executor149", pid 3615, jiffies 4294954919 (age 12.620s)

hex dump (first 32 bytes):

50 e6 22 02 81 88 ff ff e0 ff ff ff 0f 00 00 00 P.".............
10 e6 22 02 81 88 ff ff 10 e6 22 02 81 88 ff ff ..".......".....
backtrace:
[<ffffffff8262ce09>] kmalloc include/linux/slab.h:600 [inline]
[<ffffffff8262ce09>] pty_common_install+0x59/0x3d0 drivers/tty/pty.c:381
[<ffffffff8261decb>] tty_driver_install_tty drivers/tty/tty_io.c:1307 [inline]
[<ffffffff8261decb>] tty_init_dev.part.0+0x5b/0x2f0 drivers/tty/tty_io.c:1419
[<ffffffff8261e1a0>] tty_init_dev+0x40/0x60 drivers/tty/tty_io.c:1409
[<ffffffff8262cc29>] ptmx_open drivers/tty/pty.c:834 [inline]
[<ffffffff8262cc29>] ptmx_open+0xd9/0x210 drivers/tty/pty.c:800
[<ffffffff815dd68d>] chrdev_open+0x10d/0x340 fs/char_dev.c:414
[<ffffffff815cbf96>] do_dentry_open+0x1e6/0x660 fs/open.c:848
[<ffffffff815f26c1>] do_open fs/namei.c:3520 [inline]
[<ffffffff815f26c1>] path_openat+0x18a1/0x1e70 fs/namei.c:3653
[<ffffffff815f5391>] do_filp_open+0xc1/0x1b0 fs/namei.c:3680
[<ffffffff815cf88d>] do_sys_openat2+0xed/0x260 fs/open.c:1278
[<ffffffff815d02df>] do_sys_open fs/open.c:1294 [inline]
[<ffffffff815d02df>] __do_sys_openat fs/open.c:1310 [inline]
[<ffffffff815d02df>] __se_sys_openat fs/open.c:1305 [inline]
[<ffffffff815d02df>] __x64_sys_openat+0x7f/0xe0 fs/open.c:1305
[<ffffffff845ac915>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff845ac915>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

BUG: memory leak
unreferenced object 0xffff88810213d400 (size 1024):
comm "syz-executor149", pid 3615, jiffies 4294954919 (age 12.620s)

hex dump (first 32 bytes):
01 54 00 00 01 00 00 00 00 00 00 00 00 00 00 00 .T..............

40 be ca 41 81 88 ff ff 60 65 c5 84 ff ff ff ff @..A....`e......
backtrace:
[<ffffffff8261dbbc>] kmalloc include/linux/slab.h:600 [inline]
[<ffffffff8261dbbc>] kzalloc include/linux/slab.h:733 [inline]
[<ffffffff8261dbbc>] alloc_tty_struct+0x3c/0x2f0 drivers/tty/tty_io.c:3091
[<ffffffff8262ce72>] pty_common_install+0xc2/0x3d0 drivers/tty/pty.c:389
[<ffffffff8261decb>] tty_driver_install_tty drivers/tty/tty_io.c:1307 [inline]
[<ffffffff8261decb>] tty_init_dev.part.0+0x5b/0x2f0 drivers/tty/tty_io.c:1419
[<ffffffff8261e1a0>] tty_init_dev+0x40/0x60 drivers/tty/tty_io.c:1409
[<ffffffff8262cc29>] ptmx_open drivers/tty/pty.c:834 [inline]
[<ffffffff8262cc29>] ptmx_open+0xd9/0x210 drivers/tty/pty.c:800
[<ffffffff815dd68d>] chrdev_open+0x10d/0x340 fs/char_dev.c:414
[<ffffffff815cbf96>] do_dentry_open+0x1e6/0x660 fs/open.c:848
[<ffffffff815f26c1>] do_open fs/namei.c:3520 [inline]
[<ffffffff815f26c1>] path_openat+0x18a1/0x1e70 fs/namei.c:3653
[<ffffffff815f5391>] do_filp_open+0xc1/0x1b0 fs/namei.c:3680
[<ffffffff815cf88d>] do_sys_openat2+0xed/0x260 fs/open.c:1278
[<ffffffff815d02df>] do_sys_open fs/open.c:1294 [inline]
[<ffffffff815d02df>] __do_sys_openat fs/open.c:1310 [inline]
[<ffffffff815d02df>] __se_sys_openat fs/open.c:1305 [inline]
[<ffffffff815d02df>] __x64_sys_openat+0x7f/0xe0 fs/open.c:1305
[<ffffffff845ac915>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff845ac915>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.