memory leak in dma_buf_ioctl

[Dmitry Vyukov]

On Wed, Jul 24, 2019 at 11:48 AM syzbot
<syzbot+b2098bc44728a4efb3e9 at syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    abdfd52a Merge tag 'armsoc-defconfig' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=131441d0600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d31de3d88059b7fa
> dashboard link: https://syzkaller.appspot.com/bug?extid=b2098bc44728a4efb3e9
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12526e58600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161784f0600000

+drivers/dma-buf/dma-buf.c maintainers

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b2098bc44728a4efb3e9 at syzkaller.appspotmail.com
>
> executing program
> executing program
> executing program
> executing program
> executing program
> BUG: memory leak
> unreferenced object 0xffff888114034680 (size 32):
>    comm "syz-executor110", pid 6894, jiffies 4294947136 (age 13.580s)
>    hex dump (first 32 bytes):
>      00 64 6d 61 62 75 66 3a 00 00 00 00 00 00 00 00  .dmabuf:........
>      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>    backtrace:
>      [<00000000d259834b>] kmemleak_alloc_recursive
> /./include/linux/kmemleak.h:43 [inline]
>      [<00000000d259834b>] slab_post_alloc_hook /mm/slab.h:522 [inline]
>      [<00000000d259834b>] slab_alloc /mm/slab.c:3319 [inline]
>      [<00000000d259834b>] __do_kmalloc /mm/slab.c:3653 [inline]
>      [<00000000d259834b>] __kmalloc_track_caller+0x165/0x300 /mm/slab.c:3670
>      [<00000000ab207ec1>] memdup_user+0x26/0xa0 /mm/util.c:165
>      [<00000000c0909d36>] strndup_user+0x62/0x80 /mm/util.c:224
>      [<00000000a34a2d25>] dma_buf_set_name /drivers/dma-buf/dma-buf.c:331
> [inline]
>      [<00000000a34a2d25>] dma_buf_ioctl+0x60/0x1b0
> /drivers/dma-buf/dma-buf.c:391
>      [<00000000d7817662>] vfs_ioctl /fs/ioctl.c:46 [inline]
>      [<00000000d7817662>] file_ioctl /fs/ioctl.c:509 [inline]
>      [<00000000d7817662>] do_vfs_ioctl+0x62a/0x810 /fs/ioctl.c:696
>      [<00000000d24a671a>] ksys_ioctl+0x86/0xb0 /fs/ioctl.c:713
>      [<00000000bd810f5d>] __do_sys_ioctl /fs/ioctl.c:720 [inline]
>      [<00000000bd810f5d>] __se_sys_ioctl /fs/ioctl.c:718 [inline]
>      [<00000000bd810f5d>] __x64_sys_ioctl+0x1e/0x30 /fs/ioctl.c:718
>      [<000000005a8e86d5>] do_syscall_64+0x76/0x1a0
> /arch/x86/entry/common.c:296
>      [<000000007d83529f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> BUG: memory leak
> unreferenced object 0xffff888113b044a0 (size 32):
>    comm "syz-executor110", pid 6895, jiffies 4294947728 (age 7.660s)
>    hex dump (first 32 bytes):
>      00 64 6d 61 62 75 66 3a 00 00 00 00 00 00 00 00  .dmabuf:........
>      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>    backtrace:
>      [<00000000d259834b>] kmemleak_alloc_recursive
> /./include/linux/kmemleak.h:43 [inline]
>      [<00000000d259834b>] slab_post_alloc_hook /mm/slab.h:522 [inline]
>      [<00000000d259834b>] slab_alloc /mm/slab.c:3319 [inline]
>      [<00000000d259834b>] __do_kmalloc /mm/slab.c:3653 [inline]
>      [<00000000d259834b>] __kmalloc_track_caller+0x165/0x300 /mm/slab.c:3670
>      [<00000000ab207ec1>] memdup_user+0x26/0xa0 /mm/util.c:165
>      [<00000000c0909d36>] strndup_user+0x62/0x80 /mm/util.c:224
>      [<00000000a34a2d25>] dma_buf_set_name /drivers/dma-buf/dma-buf.c:331
> [inline]
>      [<00000000a34a2d25>] dma_buf_ioctl+0x60/0x1b0
> /drivers/dma-buf/dma-buf.c:391
>      [<00000000d7817662>] vfs_ioctl /fs/ioctl.c:46 [inline]
>      [<00000000d7817662>] file_ioctl /fs/ioctl.c:509 [inline]
>      [<00000000d7817662>] do_vfs_ioctl+0x62a/0x810 /fs/ioctl.c:696
>      [<00000000d24a671a>] ksys_ioctl+0x86/0xb0 /fs/ioctl.c:713
>      [<00000000bd810f5d>] __do_sys_ioctl /fs/ioctl.c:720 [inline]
>      [<00000000bd810f5d>] __se_sys_ioctl /fs/ioctl.c:718 [inline]
>      [<00000000bd810f5d>] __x64_sys_ioctl+0x1e/0x30 /fs/ioctl.c:718
>      [<000000005a8e86d5>] do_syscall_64+0x76/0x1a0
> /arch/x86/entry/common.c:296
>      [<000000007d83529f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
>
>
> ---
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