Re: [syzbot] [dri?] KASAN: slab-use-after-free Read in drm_gem_object_release_handle

[syzbot <syzbot+b2e951687503f32f74ce@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in drm_gem_object_release_handle

==================================================================
BUG: KASAN: slab-use-after-free in drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374
Read of size 8 at addr ffff888058ae0288 by task syz.1.26/6493

CPU: 1 UID: 0 PID: 6493 Comm: syz.1.26 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374
 drm_gem_object_release_idr_handle+0x99/0xb0 drivers/gpu/drm/drm_gem.c:406
 idr_for_each+0x1c6/0x2a0 lib/idr.c:210
 drm_gem_release+0x28/0x40 drivers/gpu/drm/drm_gem.c:1104
 drm_file_free+0x729/0xa00 drivers/gpu/drm/drm_file.c:261
 drm_close_helper drivers/gpu/drm/drm_file.c:290 [inline]
 drm_release+0x2de/0x3f0 drivers/gpu/drm/drm_file.c:438
 __fput+0x44f/0xa60 fs/file_table.c:510
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f384cb9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffea5f94ac8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffea5f94bb0 RCX: 00007f384cb9c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001ea55 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b30e20000 R11: 0000000000000246 R12: 00007ffea5f94bf0
R13: 00007f384ce1609c R14: 000000000001ea8b R15: 00007f384ce16090
 </TASK>

Allocated by task 6494:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5380
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 __drm_gem_shmem_create+0xc4/0x2e0 drivers/gpu/drm/drm_gem_shmem_helper.c:130
 drm_gem_shmem_create drivers/gpu/drm/drm_gem_shmem_helper.c:157 [inline]
 drm_gem_shmem_create_with_handle drivers/gpu/drm/drm_gem_shmem_helper.c:460 [inline]
 drm_gem_shmem_dumb_create+0x72/0x120 drivers/gpu/drm/drm_gem_shmem_helper.c:549
 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:227 [inline]
 drm_mode_create_dumb_ioctl+0x2bd/0x340 drivers/gpu/drm/drm_dumb_buffers.c:236
 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804
 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6495:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6483
 drm_gem_handle_delete+0x84/0xa0 drivers/gpu/drm/drm_gem.c:434
 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804
 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888058ae0000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 648 bytes inside of
 freed 1024-byte region [ffff888058ae0000, ffff888058ae0400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888058ae1800 pfn:0x58ae0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88813fea7dc0 ffffea0000a1de10 ffff88813fea6888
raw: ffff888058ae1800 0000000800100003 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fea7dc0 ffffea0000a1de10 ffff88813fea6888
head: ffff888058ae1800 0000000800100003 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea000162b801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 13, tgid 13 (kworker/u8:1), ts 125536208154, free_ts 123699282996
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 ieee802_11_parse_elems_full+0x159/0x2ab0 net/mac80211/parse.c:1051
 ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2480 [inline]
 ieee80211_inform_bss+0x161/0x1160 net/mac80211/scan.c:79
 rdev_inform_bss net/wireless/rdev-ops.h:418 [inline]
 cfg80211_inform_single_bss_data+0xd08/0x1b70 net/wireless/scan.c:2372
 cfg80211_inform_bss_data+0x266/0x3c40 net/wireless/scan.c:3226
 cfg80211_inform_bss_frame_data+0x3c7/0x760 net/wireless/scan.c:3317
 ieee80211_bss_info_update+0x794/0xa40 net/mac80211/scan.c:230
 ieee80211_rx_bss_info net/mac80211/ibss.c:1094 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1575 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x1901/0x2cd0 net/mac80211/ibss.c:1602
 ieee80211_iface_process_skb net/mac80211/iface.c:1748 [inline]
 ieee80211_iface_work+0x84e/0x1340 net/mac80211/iface.c:1802
 cfg80211_wiphy_work+0x2ab/0x4a0 net/wireless/core.c:440
page last free pid 6361 tgid 6361 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __slab_free+0x263/0x2b0 mm/slub.c:5573
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x316/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3818
 ip6_route_add+0x49/0x1b0 net/ipv6/route.c:3947
 addrconf_prefix_route+0x3a2/0x480 net/ipv6/addrconf.c:2487
 add_v4_addrs+0x5a6/0x7e0 net/ipv6/addrconf.c:3264
 addrconf_sit_config net/ipv6/addrconf.c:3520 [inline]
 addrconf_init_auto_addrs+0x248/0xa50 net/ipv6/addrconf.c:3558
 addrconf_notify+0xb1e/0x1050 net/ipv6/addrconf.c:3744
 notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9820
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9849

Memory state around the buggy address:
 ffff888058ae0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888058ae0200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888058ae0280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888058ae0300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888058ae0380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         d60bc140 Merge tag 'pwrseq-updates-for-v7.1-rc1' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d304ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=85bd86f990609a1
dashboard link: https://syzkaller.appspot.com/bug?extid=b2e951687503f32f74ce
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11597b02580000