[alsa-devel] sound: memory leak in snd_seq_pool_init

[Dmitry Vyukov]

On Mon, Feb 15, 2016 at 11:21 AM, Takashi Iwai <tiwai at suse.de> wrote:
> On Mon, 15 Feb 2016 10:35:22 +0100,
> Dmitry Vyukov wrote:
>>
>> Hello,
>>
>> The following program causes memory leak of a 24K object allocated in
>> snd_seq_pool_init:
>>
>> // autogenerated by syzkaller (http://github.com/google/syzkaller)
>> #include <pthread.h>
>> #include <stdint.h>
>> #include <string.h>
>> #include <sys/syscall.h>
>> #include <unistd.h>
>>
>> long r[148];
>>
>> void* thr(void* arg)
>> {
>>   switch ((long)arg) {
>>   case 0:
>>     r[0] = syscall(SYS_mmap, 0x20000000ul, 0xe000ul, 0x3ul, 0x32ul,
>>                    0xfffffffffffffffful, 0x0ul);
>>     break;
>>   case 1:
>>     r[2] = syscall(SYS_open, "/dev/snd/seq", 0x1ul, 0, 0, 0);
>>     break;
>>   case 2:
>>     *(uint32_t*)0x20008a90 = (uint32_t)0x6;
>>     *(uint32_t*)0x20008a94 = (uint32_t)0x4;
>>     *(uint32_t*)0x20008a98 = (uint32_t)0x200;
>>     *(uint8_t*)0x20008a9c = (uint8_t)0xfa5;
>>     *(uint8_t*)0x20008a9d = (uint8_t)0x100000000;
>>     *(uint8_t*)0x20008a9e = (uint8_t)0x0;
>>     *(uint8_t*)0x20008a9f = (uint8_t)0x3;
>>     *(uint8_t*)0x20008aa0 = (uint8_t)0x1;
>>     *(uint8_t*)0x20008aa1 = (uint8_t)0x1;
>>     *(uint8_t*)0x20008aa2 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aa3 = (uint8_t)0x40;
>>     *(uint8_t*)0x20008aa4 = (uint8_t)0x9;
>>     *(uint8_t*)0x20008aa5 = (uint8_t)0x9;
>>     *(uint8_t*)0x20008aa6 = (uint8_t)0x6;
>>     *(uint8_t*)0x20008aa7 = (uint8_t)0x80;
>>     *(uint8_t*)0x20008aa8 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aa9 = (uint8_t)0x5d34b2c3;
>>     *(uint8_t*)0x20008aaa = (uint8_t)0x3a7;
>>     *(uint8_t*)0x20008aab = (uint8_t)0x9;
>>     *(uint8_t*)0x20008aac = (uint8_t)0x8d62;
>>     *(uint8_t*)0x20008aad = (uint8_t)0x5;
>>     *(uint8_t*)0x20008aae = (uint8_t)0x7;
>>     *(uint8_t*)0x20008aaf = (uint8_t)0x20;
>>     *(uint8_t*)0x20008ab0 = (uint8_t)0x8;
>>     *(uint8_t*)0x20008ab1 = (uint8_t)0x7;
>>     *(uint8_t*)0x20008ab2 = (uint8_t)0xfffffffffffffffc;
>>     *(uint8_t*)0x20008ab3 = (uint8_t)0x7;
>>     *(uint8_t*)0x20008ab4 = (uint8_t)0x7ff;
>>     *(uint8_t*)0x20008ab5 = (uint8_t)0x1;
>>     *(uint8_t*)0x20008ab6 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ab7 = (uint8_t)0x9;
>>     *(uint8_t*)0x20008ab8 = (uint8_t)0x6;
>>     *(uint8_t*)0x20008ab9 = (uint8_t)0xfffffffffffffe00;
>>     *(uint8_t*)0x20008aba = (uint8_t)0x1000;
>>     *(uint8_t*)0x20008abb = (uint8_t)0xfffffffffffffffb;
>>     *(uint8_t*)0x20008abc = (uint8_t)0xcfd3;
>>     *(uint8_t*)0x20008abd = (uint8_t)0x101;
>>     *(uint8_t*)0x20008abe = (uint8_t)0x9;
>>     *(uint8_t*)0x20008abf = (uint8_t)0xfffffffffffffffc;
>>     *(uint8_t*)0x20008ac0 = (uint8_t)0xf2;
>>     *(uint8_t*)0x20008ac1 = (uint8_t)0x6;
>>     *(uint8_t*)0x20008ac2 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ac3 = (uint8_t)0x7fffffff;
>>     *(uint8_t*)0x20008ac4 = (uint8_t)0x4;
>>     *(uint8_t*)0x20008ac5 = (uint8_t)0x5;
>>     *(uint8_t*)0x20008ac6 = (uint8_t)0x4;
>>     *(uint8_t*)0x20008ac7 = (uint8_t)0x4;
>>     *(uint8_t*)0x20008ac8 = (uint8_t)0x20;
>>     *(uint8_t*)0x20008ac9 = (uint8_t)0x401;
>>     *(uint8_t*)0x20008aca = (uint8_t)0x6;
>>     *(uint8_t*)0x20008acb = (uint8_t)0x6;
>>     *(uint8_t*)0x20008acc = (uint8_t)0x5;
>>     *(uint8_t*)0x20008acd = (uint8_t)0x3;
>>     *(uint8_t*)0x20008ace = (uint8_t)0xfffffffffffffffc;
>>     *(uint8_t*)0x20008acf = (uint8_t)0xb0c;
>>     *(uint8_t*)0x20008ad0 = (uint8_t)0x2;
>>     *(uint8_t*)0x20008ad1 = (uint8_t)0xfffffffffffffff9;
>>     *(uint8_t*)0x20008ad2 = (uint8_t)0x8000;
>>     *(uint8_t*)0x20008ad3 = (uint8_t)0x5;
>>     *(uint8_t*)0x20008ad4 = (uint8_t)0xb0c;
>>     *(uint8_t*)0x20008ad5 = (uint8_t)0xfffffffffffffeff;
>>     *(uint8_t*)0x20008ad6 = (uint8_t)0x5;
>>     *(uint8_t*)0x20008ad7 = (uint8_t)0x101;
>>     *(uint8_t*)0x20008ad8 = (uint8_t)0xbfd;
>>     *(uint8_t*)0x20008ad9 = (uint8_t)0x7ff;
>>     *(uint8_t*)0x20008ada = (uint8_t)0x7f;
>>     *(uint8_t*)0x20008adb = (uint8_t)0x5;
>>     *(uint32_t*)0x20008adc = (uint32_t)0x6;
>>     *(uint8_t*)0x20008ae0 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae1 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae2 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae3 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae4 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae5 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae6 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae7 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae8 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008ae9 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aea = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aeb = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aec = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aed = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aee = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aef = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af0 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af1 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af2 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af3 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af4 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af5 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af6 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af7 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af8 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008af9 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008afa = (uint8_t)0x0;
>>     *(uint8_t*)0x20008afb = (uint8_t)0x0;
>>     *(uint8_t*)0x20008afc = (uint8_t)0x0;
>>     *(uint8_t*)0x20008afd = (uint8_t)0x0;
>>     *(uint8_t*)0x20008afe = (uint8_t)0x0;
>>     *(uint8_t*)0x20008aff = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b00 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b01 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b02 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b03 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b04 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b05 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b06 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b07 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b08 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b09 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0a = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0b = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0c = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0d = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0e = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b0f = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b10 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b11 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b12 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b13 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b14 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b15 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b16 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b17 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b18 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b19 = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b1a = (uint8_t)0x0;
>>     *(uint8_t*)0x20008b1b = (uint8_t)0x0;
>>     r[131] =
>>         syscall(SYS_ioctl, r[2], 0xc08c5332ul, 0x20008a90ul, 0, 0, 0);
>>     break;
>>   case 3:
>>     *(uint32_t*)0x20009fd0 = (uint32_t)0x30;
>>     *(uint32_t*)0x20009fd4 = (uint32_t)0xfff;
>>     *(uint64_t*)0x20009fd8 = (uint64_t)0x0;
>>     *(uint64_t*)0x20009fe0 = (uint64_t)0x1ce;
>>     *(uint64_t*)0x20009fe8 = (uint64_t)0x2;
>>     *(uint64_t*)0x20009ff0 = (uint64_t)0xff;
>>     *(uint32_t*)0x20009ff8 = (uint32_t)0x10001;
>>     r[139] = syscall(SYS_write, r[2], 0x20009fd0ul, 0x30ul, 0, 0, 0);
>>     break;
>>   case 4:
>>     *(uint32_t*)0x2000bb13 = (uint32_t)0x30;
>>     *(uint32_t*)0x2000bb17 = (uint32_t)0x2;
>>     *(uint64_t*)0x2000bb1b = (uint64_t)0x0;
>>     *(uint64_t*)0x2000bb23 = (uint64_t)0x53;
>>     *(uint64_t*)0x2000bb2b = (uint64_t)0xfffffffffffffbff;
>>     *(uint64_t*)0x2000bb33 = (uint64_t)0x5;
>>     *(uint32_t*)0x2000bb3b = (uint32_t)0x5;
>>     r[147] = syscall(SYS_write, r[2], 0x2000bb13ul, 0x30ul, 0, 0, 0);
>>     break;
>>   }
>>   return 0;
>> }
>>
>> int main()
>> {
>>   long i;
>>   pthread_t th[5];
>>
>>   memset(r, -1, sizeof(r));
>>   for (i = 0; i < 5; i++) {
>>     pthread_create(&th[i], 0, thr, (void*)i);
>>     usleep(10000);
>>   }
>>   for (i = 0; i < 5; i++) {
>>     pthread_create(&th[i], 0, thr, (void*)i);
>>     if (i % 2 == 0)
>>       usleep(10000);
>>   }
>>   usleep(100000);
>>   return 0;
>> }
>>
>>
>>
>> unreferenced object 0xffffc90003663000 (size 24000):
>>   comm "a.out", pid 1770, jiffies 4295717383 (age 7.217s)
>>   hex dump (first 32 bytes):
>>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>>   backtrace:
>>     [<ffffffff86644303>] kmemleak_alloc+0x63/0xa0 mm/kmemleak.c:916
>>     [<ffffffff81720da9>] __vmalloc_node_range+0x469/0x640 mm/vmalloc.c:1682
>>     [<     inline     >] __vmalloc_node mm/vmalloc.c:1710
>>     [<     inline     >] __vmalloc_node_flags mm/vmalloc.c:1724
>>     [<ffffffff8172104b>] vmalloc+0x5b/0x70 mm/vmalloc.c:1739
>>     [<ffffffff852b92cb>] snd_seq_pool_init+0xbb/0x300
>> sound/core/seq/seq_memory.c:389
>>     [<ffffffff852b5ff4>] snd_seq_write+0x4d4/0x570
>> sound/core/seq/seq_clientmgr.c:1029
>>     [<ffffffff817bbfc3>] __vfs_write+0x113/0x4b0 fs/read_write.c:528
>>     [<ffffffff817bda87>] vfs_write+0x167/0x4a0 fs/read_write.c:577
>>     [<     inline     >] SYSC_write fs/read_write.c:624
>>     [<ffffffff817c0d71>] SyS_write+0x111/0x220 fs/read_write.c:616
>>     [<ffffffff866613f6>] entry_SYSCALL_64_fastpath+0x16/0x7a
>> arch/x86/entry/entry_64.S:185
>>     [<ffffffffffffffff>] 0xffffffffffffffff
>>
>>
>> On commit 388f7b1d6e8ca06762e2454d28d6c3c55ad0fe95 (4.5-rc3)
>
> Hm, this looks like the issue triggered by concurrent writes to the
> same client.  Does the patch fix the problem?

Yes, it fixes the leak for me.

Tested-by: Dmitry Vyukov <dvyukov at google.com>


>
>
> thanks,
>
> Takashi
>
> ---
> diff --git a/sound/core/seq/seq_memory.c b/sound/core/seq/seq_memory.c
> index 801076687bb1..c850345c43b5 100644
> --- a/sound/core/seq/seq_memory.c
> +++ b/sound/core/seq/seq_memory.c
> @@ -383,15 +383,20 @@ int snd_seq_pool_init(struct snd_seq_pool *pool)
>
>         if (snd_BUG_ON(!pool))
>                 return -EINVAL;
> -       if (pool->ptr)                  /* should be atomic? */
> -               return 0;
>
> -       pool->ptr = vmalloc(sizeof(struct snd_seq_event_cell) * pool->size);
> -       if (!pool->ptr)
> +       cellptr = vmalloc(sizeof(struct snd_seq_event_cell) * pool->size);
> +       if (!cellptr)
>                 return -ENOMEM;
>
>         /* add new cells to the free cell list */
>         spin_lock_irqsave(&pool->lock, flags);
> +       if (pool->ptr) {
> +               spin_unlock_irqrestore(&pool->lock, flags);
> +               vfree(cellptr);
> +               return 0;
> +       }
> +
> +       pool->ptr = cellptr;
>         pool->free = NULL;
>
>         for (cell = 0; cell < pool->size; cell++) {