Re: WARNING in idr_destroy

[Qiujun Huang]

We need to get idr_mutex first for idr_alloc.

diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
index b481cafdde28..aa72c8344ec7 100644
--- a/drivers/gpu/drm/drm_lease.c
+++ b/drivers/gpu/drm/drm_lease.c
@@ -420,6 +420,7 @@ static int fill_object_idr(struct drm_device *dev,

        /* add their IDs to the lease request - taking into account
           universal planes */
+       mutex_lock(&dev->mode_config.idr_mutex);
        for (o = 0; o < object_count; o++) {
                struct drm_mode_object *obj = objects[o];
                u32 object_id = objects[o]->id;
@@ -457,6 +458,7 @@ static int fill_object_idr(struct drm_device *dev,
                        }
                }
        }
+       mutex_unlock(&dev->mode_config.idr_mutex);

        ret = 0;
 out_free_objects:

On Tue, Mar 3, 2020 at 3:50 PM syzbot
<syzbot+05835159fe322770fe3d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10e978e3e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5d2e033af114153f
> dashboard link: https://syzkaller.appspot.com/bug?extid=05835159fe322770fe3d
> compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14e978e3e00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10b1a819e00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+05835159fe322770fe3d@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
> R13: 00007fc6b3362d90 R14: 0000000000000004 R15: 000000000000002d
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 12260 at lib/radix-tree.c:682 radix_tree_free_nodes lib/radix-tree.c:682 [inline]
> WARNING: CPU: 0 PID: 12260 at lib/radix-tree.c:682 idr_destroy+0x1ae/0x260 lib/radix-tree.c:1572
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 12260 Comm: syz-executor386 Not tainted 5.6.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1fb/0x318 lib/dump_stack.c:118
>  panic+0x264/0x7a9 kernel/panic.c:221
>  __warn+0x209/0x210 kernel/panic.c:582
>  report_bug+0x1b6/0x2f0 lib/bug.c:195
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  do_error_trap+0xcf/0x1c0 arch/x86/kernel/traps.c:267
>  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:286
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:radix_tree_free_nodes lib/radix-tree.c:682 [inline]
> RIP: 0010:idr_destroy+0x1ae/0x260 lib/radix-tree.c:1572
> Code: b5 63 f9 48 89 df 48 c7 c6 c0 0a 13 88 e8 6a ce 50 f9 4c 3b 65 b8 74 57 e8 cf b5 63 f9 4d 89 fc e9 67 ff ff ff e8 c2 b5 63 f9 <0f> 0b eb d5 89 f9 80 e1 07 38 c1 7c 84 e8 c0 de a0 f9 e9 7a ff ff
> RSP: 0018:ffffc90005107ba0 EFLAGS: 00010293
> RAX: ffffffff881363be RBX: ffff888087dba998 RCX: ffff888094062300
> RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff888087dba988
> RBP: ffffc90005107be8 R08: ffffffff88136330 R09: ffffed1012a78181
> R10: ffffed1012a78181 R11: 0000000000000000 R12: ffff888087dba980
> R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000
>  drm_mode_create_lease_ioctl+0x1347/0x1860 drivers/gpu/drm/drm_lease.c:583
>  drm_ioctl_kernel+0x2cf/0x410 drivers/gpu/drm/drm_ioctl.c:786
>  drm_ioctl+0x52f/0x890 drivers/gpu/drm/drm_ioctl.c:886
>  vfs_ioctl fs/ioctl.c:47 [inline]
>  ksys_ioctl fs/ioctl.c:763 [inline]
>  __do_sys_ioctl fs/ioctl.c:772 [inline]
>  __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770
>  __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770
>  do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x44a4b9
> Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 9b cc fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fc6b3362d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 000000000044a4b9
> RDX: 0000000020000040 RSI: ffffffffffffffc6 RDI: 0000000000000003
> RBP: 00000000006dbc20 R08: 0000000000000001 R09: 0000000000000039
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
> R13: 00007fc6b3362d90 R14: 0000000000000004 R15: 000000000000002d
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
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>
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