tty: memory leak in tty_open

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Dmitry Vyukov

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Apr 4, 2016, 4:56:39 AM4/4/16
to Greg Kroah-Hartman, Jiri Slaby, LKML, syzkaller, Kostya Serebryany, Alexander Potapenko, Sasha Levin
Hello,

The following program causes a memory leak:

unreferenced object 0xffff8800643c3168 (size 2048):
comm "syz-executor", pid 29328, jiffies 4295358628 (age 32.380s)
hex dump (first 32 bytes):
01 54 00 00 0c 00 00 00 88 27 e1 67 00 88 ff ff .T.......'.g....
88 1f 54 68 00 88 ff ff 40 b1 f0 86 ff ff ff ff ..Th....@.......
backtrace:
[<ffffffff86798093>] kmemleak_alloc+0x63/0xa0 mm/kmemleak.c:915
[< inline >] kmemleak_alloc_recursive include/linux/kmemleak.h:47
[< inline >] slab_post_alloc_hook mm/slab.h:406
[< inline >] slab_alloc_node mm/slub.c:2602
[< inline >] slab_alloc mm/slub.c:2610
[<ffffffff817979a0>] kmem_cache_alloc_trace+0x160/0x3d0 mm/slub.c:2627
[< inline >] kmalloc include/linux/slab.h:478
[< inline >] kzalloc include/linux/slab.h:622
[<ffffffff8304a748>] alloc_tty_struct+0x98/0x840 drivers/tty/tty_io.c:3156
[<ffffffff8304af68>] tty_init_dev+0x78/0x4b0 drivers/tty/tty_io.c:1532
[< inline >] tty_open_by_driver drivers/tty/tty_io.c:2066
[<ffffffff8304c181>] tty_open+0xde1/0x1140 drivers/tty/tty_io.c:2114
[<ffffffff81801fca>] chrdev_open+0x22a/0x4c0 fs/char_dev.c:388
[<ffffffff817ed6a2>] do_dentry_open+0x6a2/0xcb0 fs/open.c:736
[<ffffffff817f0d7b>] vfs_open+0x17b/0x1f0 fs/open.c:853
[< inline >] do_last fs/namei.c:3238
[<ffffffff8182961b>] path_openat+0x51bb/0x5ce0 fs/namei.c:3374
[<ffffffff8182d7be>] do_filp_open+0x18e/0x250 fs/namei.c:3409
[<ffffffff817f14fc>] do_sys_open+0x1fc/0x420 fs/open.c:1020
[< inline >] SYSC_open fs/open.c:1038
[<ffffffff817f174d>] SyS_open+0x2d/0x40 fs/open.c:1033


// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <pthread.h>
#include <sys/syscall.h>
#include <unistd.h>

void* thr(void* arg)
{
syscall(SYS_open, "/dev/console", 0, 0, 0, 0);
return 0;
}

int main()
{
int i;
pthread_t th[4];

for (i = 0; i < 4; i++)
pthread_create(&th[i], 0, thr, 0);
usleep(100);
return 0;
}


On commit 05cf8077e54b20dddb756eaa26f3aeb5c38dd3cf (Apr 1).

Peter Hurley

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Apr 4, 2016, 3:37:14 PM4/4/16
to Dmitry Vyukov, Greg Kroah-Hartman, Jiri Slaby, LKML, syzkaller, Kostya Serebryany, Alexander Potapenko, Sasha Levin
Hi Dmitry,

On 04/04/2016 01:56 AM, Dmitry Vyukov wrote:
> Hello,
>
> The following program causes a memory leak:

Thanks for the report. This is the same problem fixed in 4.5
There was a merge snafu; Greg has the patch in his queue that
fixes this for 4.6

Regards,
Peter Hurley

Dmitry Vyukov

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Apr 4, 2016, 4:02:33 PM4/4/16
to Peter Hurley, Greg Kroah-Hartman, Jiri Slaby, LKML, syzkaller, Kostya Serebryany, Alexander Potapenko, Sasha Levin
On Mon, Apr 4, 2016 at 9:37 PM, Peter Hurley <pe...@hurleysoftware.com> wrote:
> Hi Dmitry,
>
> On 04/04/2016 01:56 AM, Dmitry Vyukov wrote:
>> Hello,
>>
>> The following program causes a memory leak:
>
> Thanks for the report. This is the same problem fixed in 4.5
> There was a merge snafu; Greg has the patch in his queue that
> fixes this for 4.6


Thanks! Then I will wait for merge.
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