Hello,
syzbot found the following crash on:
HEAD commit: 39bed42d Merge tag 'for-linus-hmm' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=179465bee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=2646535f8818ae25 dashboard link: https://syzkaller.appspot.com/bug?extid=0dc4444774d419e916c8 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16251279e00000
The bug was bisected to:
commit 7611750784664db46d0db95631e322aeb263dde7 Author: Alex Deucher alexander.deucher@amd.com Date: Wed Jun 21 16:31:41 2017 +0000
drm/amdgpu: use kernel is_power_of_2 rather than local version
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11628df1e00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13628df1e00000 console output: https://syzkaller.appspot.com/x/log.txt?x=15628df1e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
================================================================== BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 Read of size 8 at addr ffff88809fa67908 by task syz-executor.0/14871
CPU: 0 PID: 14871 Comm: syz-executor.0 Not tainted 5.5.0-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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b349 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f871af46c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f871af476d4 RCX: 000000000045b349 RDX: 0000000020000180 RSI: 00000000c02064b2 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000285 R14: 00000000004d14d0 R15: 000000000075bf2c
Allocated by task 14871: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:670 [inline] __vgem_gem_create+0x49/0x100 drivers/gpu/drm/vgem/vgem_drv.c:165 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:194 [inline] vgem_gem_dumb_create+0xd7/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 14871: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 vgem_gem_free_object+0xbe/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:68 drm_gem_object_free+0x100/0x220 drivers/gpu/drm/drm_gem.c:983 kref_put include/linux/kref.h:65 [inline] drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline] drm_gem_object_put_unlocked+0x196/0x1c0 drivers/gpu/drm/drm_gem.c:1002 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x115/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff88809fa67800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 264 bytes inside of 1024-byte region [ffff88809fa67800, ffff88809fa67c00) The buggy address belongs to the page: page:ffffea00027e99c0 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 raw: 00fffe0000000200 ffffea0002293548 ffffea00023e1f08 ffff8880aa400c40 raw: 0000000000000000 ffff88809fa67000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff88809fa67800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809fa67880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809fa67900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff88809fa67980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809fa67a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
--- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
I don't totally understand the stack trace but I do see a double free bug.
drivers/gpu/drm/vgem/vgem_drv.c 186 static struct drm_gem_object *vgem_gem_create(struct drm_device *dev, 187 struct drm_file *file, 188 unsigned int *handle, 189 unsigned long size) 190 { 191 struct drm_vgem_gem_object *obj; 192 int ret; 193 194 obj = __vgem_gem_create(dev, size);
obj->base.handle_count is zero.
195 if (IS_ERR(obj)) 196 return ERR_CAST(obj); 197 198 ret = drm_gem_handle_create(file, &obj->base, handle);
We bump it +1 and then the error handling calls drm_gem_object_handle_put_unlocked(obj); which calls drm_gem_object_put_unlocked(); which frees obj.
199 drm_gem_object_put_unlocked(&obj->base);
So this is a double free. Could someone check my thinking and send a patch? It's just a one liner. Otherwise I can send it on Monday.
200 if (ret) 201 return ERR_PTR(ret); 202 203 return &obj->base; 204 }
regards, dan carpenter
syzbot has found a reproducer for the following crash on:
HEAD commit: 94f2630b Merge tag '5.6-rc-small-smb3-fix-for-stable' of g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11d6c776e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=99db4e42d047be3 dashboard link: https://syzkaller.appspot.com/bug?extid=0dc4444774d419e916c8 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=152385bee00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=123210a1e00000
The bug was bisected to:
commit 7611750784664db46d0db95631e322aeb263dde7 Author: Alex Deucher alexander.deucher@amd.com Date: Wed Jun 21 16:31:41 2017 +0000
drm/amdgpu: use kernel is_power_of_2 rather than local version
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11628df1e00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13628df1e00000 console output: https://syzkaller.appspot.com/x/log.txt?x=15628df1e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
================================================================== BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 Read of size 8 at addr ffff88809a2ee908 by task syz-executor815/10244
CPU: 1 PID: 10244 Comm: syz-executor815 Not tainted 5.5.0-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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x44c3e9 Code: e8 8c e7 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 1b cc fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f40263e9db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000006ddc58 RCX: 000000000044c3e9 RDX: 0000000020000000 RSI: 00000000c02064b2 RDI: 0000000000000004 RBP: 00000000006ddc50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc5c R13: 00007ffed0d4362f R14: 00007f40263ea9c0 R15: 00000000006ddc5c
Allocated by task 10244: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:670 [inline] __vgem_gem_create+0x49/0x100 drivers/gpu/drm/vgem/vgem_drv.c:165 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:194 [inline] vgem_gem_dumb_create+0xd7/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 10244: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 vgem_gem_free_object+0xbe/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:68 drm_gem_object_free+0x100/0x220 drivers/gpu/drm/drm_gem.c:983 kref_put include/linux/kref.h:65 [inline] drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline] drm_gem_object_put_unlocked+0x196/0x1c0 drivers/gpu/drm/drm_gem.c:1002 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x115/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff88809a2ee800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 264 bytes inside of 1024-byte region [ffff88809a2ee800, ffff88809a2eec00) The buggy address belongs to the page: page:ffffea000268bb80 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002816448 ffffea0002551bc8 ffff8880aa400c40 raw: 0000000000000000 ffff88809a2ee000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff88809a2ee800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809a2ee880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809a2ee900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff88809a2ee980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809a2eea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
On Fri, Jan 31, 2020 at 11:28 PM syzbot syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com wrote:
Hello,
syzbot found the following crash on:
HEAD commit: 39bed42d Merge tag 'for-linus-hmm' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=179465bee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=2646535f8818ae25 dashboard link: https://syzkaller.appspot.com/bug?extid=0dc4444774d419e916c8 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16251279e00000
The bug was bisected to:
commit 7611750784664db46d0db95631e322aeb263dde7 Author: Alex Deucher alexander.deucher@amd.com Date: Wed Jun 21 16:31:41 2017 +0000
drm/amdgpu: use kernel is_power_of_2 rather than local versionbisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11628df1e00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13628df1e00000 console output: https://syzkaller.appspot.com/x/log.txt?x=15628df1e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
Aside: This bisect line is complete nonsense ... I'm kinda at the point where I'm assuming that syzbot bisect results are garbage, which is maybe not what we want. I guess much stricter filtering for noise is needed, dunno. -Danile
================================================================== BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 Read of size 8 at addr ffff88809fa67908 by task syz-executor.0/14871
CPU: 0 PID: 14871 Comm: syz-executor.0 Not tainted 5.5.0-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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b349 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f871af46c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f871af476d4 RCX: 000000000045b349 RDX: 0000000020000180 RSI: 00000000c02064b2 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000285 R14: 00000000004d14d0 R15: 000000000075bf2c
Allocated by task 14871: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:670 [inline] __vgem_gem_create+0x49/0x100 drivers/gpu/drm/vgem/vgem_drv.c:165 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:194 [inline] vgem_gem_dumb_create+0xd7/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 14871: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 vgem_gem_free_object+0xbe/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:68 drm_gem_object_free+0x100/0x220 drivers/gpu/drm/drm_gem.c:983 kref_put include/linux/kref.h:65 [inline] drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline] drm_gem_object_put_unlocked+0x196/0x1c0 drivers/gpu/drm/drm_gem.c:1002 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x115/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff88809fa67800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 264 bytes inside of 1024-byte region [ffff88809fa67800, ffff88809fa67c00) The buggy address belongs to the page: page:ffffea00027e99c0 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 raw: 00fffe0000000200 ffffea0002293548 ffffea00023e1f08 ffff8880aa400c40 raw: 0000000000000000 ffff88809fa67000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff88809fa67800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809fa67880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809fa67900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ffff88809fa67980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809fa67a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
On Sun, Feb 02, 2020 at 02:19:18PM +0100, Daniel Vetter wrote:
On Fri, Jan 31, 2020 at 11:28 PM syzbot syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com wrote:
Hello,
syzbot found the following crash on:
HEAD commit: 39bed42d Merge tag 'for-linus-hmm' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=179465bee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=2646535f8818ae25 dashboard link: https://syzkaller.appspot.com/bug?extid=0dc4444774d419e916c8 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16251279e00000
The bug was bisected to:
commit 7611750784664db46d0db95631e322aeb263dde7 Author: Alex Deucher alexander.deucher@amd.com Date: Wed Jun 21 16:31:41 2017 +0000
drm/amdgpu: use kernel is_power_of_2 rather than local versionbisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11628df1e00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13628df1e00000 console output: https://syzkaller.appspot.com/x/log.txt?x=15628df1e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
Aside: This bisect line is complete nonsense ... I'm kinda at the point where I'm assuming that syzbot bisect results are garbage, which is maybe not what we want. I guess much stricter filtering for noise is needed, dunno. -Danile
With race conditions the git bisect is often nonsense.
regards, dan carpenter
Am 03.02.20 um 10:06 schrieb Dan Carpenter:
On Sun, Feb 02, 2020 at 02:19:18PM +0100, Daniel Vetter wrote:
On Fri, Jan 31, 2020 at 11:28 PM syzbot syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com wrote:
Hello,
syzbot found the following crash on:
HEAD commit: 39bed42d Merge tag 'for-linus-hmm' of git://git.kernel.org.. git tree: upstream console output: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller.... kernel config: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller.... dashboard link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller.... compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller....
The bug was bisected to:
commit 7611750784664db46d0db95631e322aeb263dde7 Author: Alex Deucher alexander.deucher@amd.com Date: Wed Jun 21 16:31:41 2017 +0000
drm/amdgpu: use kernel is_power_of_2 rather than local versionbisection log: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller.... final crash: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller.... console output: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsyzkaller....
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
Aside: This bisect line is complete nonsense ... I'm kinda at the point where I'm assuming that syzbot bisect results are garbage, which is maybe not what we want. I guess much stricter filtering for noise is needed, dunno. -Danile
With race conditions the git bisect is often nonsense.
Which makes sense, but we can still try to sanitize the result. I'm not familiar with the test case, but I think it doesn't even compile the amdgpu driver.
So skipping all patches of stuff you don't even compile would make not only the result of bisecting quite a bit more reliable, but also speed the process up quite a bit.
But no good idea to how teach that to a compile bot or the git bisect command.
Regards, Christian.
regards, dan carpenter
dri-devel@lists.freedesktop.org
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Christian König -
Dan Carpenter -
Daniel Vetter -
syzbot