==================================================================
BUG: KASAN: use-after-free in fb_mode_is_equal+0x284/0x2f0 drivers/video/fbdev/core/modedb.c:924
Read of size 4 at addr ffff888021a0309c by task syz-executor.3/30595

CPU: 0 PID: 30595 Comm: syz-executor.3 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 fb_mode_is_equal+0x284/0x2f0 drivers/video/fbdev/core/modedb.c:924
 fbcon_mode_deleted+0x13d/0x1d0 drivers/video/fbdev/core/fbcon.c:2718
 fb_set_var+0xae1/0xda0 drivers/video/fbdev/core/fbmem.c:975
 do_fb_ioctl+0x2f9/0x690 drivers/video/fbdev/core/fbmem.c:1108
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe6f0a37188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000020000180 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 0000000000a9fb1f R14: 00007fe6f0a37300 R15: 0000000000022000

Allocated by task 9781:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 fb_add_videomode drivers/video/fbdev/core/modedb.c:1073 [inline]
 fb_add_videomode+0x2fb/0x610 drivers/video/fbdev/core/modedb.c:1057
 fb_set_var+0x631/0xda0 drivers/video/fbdev/core/fbmem.c:1049
 do_fb_ioctl+0x2f9/0x690 drivers/video/fbdev/core/fbmem.c:1108
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 30583:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:229 [inline]
 slab_free_hook mm/slub.c:1650 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1675
 slab_free mm/slub.c:3235 [inline]
 kfree+0xeb/0x650 mm/slub.c:4295
 fb_delete_videomode+0x3d2/0x570 drivers/video/fbdev/core/modedb.c:1104
 fb_set_var+0xaf1/0xda0 drivers/video/fbdev/core/fbmem.c:978
 do_fb_ioctl+0x2f9/0x690 drivers/video/fbdev/core/fbmem.c:1108
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3594
 cfg80211_update_known_bss+0x833/0xa60 net/wireless/scan.c:1661
 cfg80211_bss_update+0xef/0x1e10 net/wireless/scan.c:1708
 cfg80211_inform_single_bss_frame_data+0x6e8/0xee0 net/wireless/scan.c:2414
 cfg80211_inform_bss_frame_data+0xa7/0xb10 net/wireless/scan.c:2447
 ieee80211_bss_info_update+0x374/0xb70 net/mac80211/scan.c:190
 ieee80211_rx_bss_info net/mac80211/ibss.c:1126 [inline]
 ieee80211_rx_mgmt_probe_beacon+0xcc6/0x17c0 net/mac80211/ibss.c:1615
 ieee80211_ibss_rx_queued_mgmt+0xd30/0x1610 net/mac80211/ibss.c:1642
 ieee80211_iface_process_skb net/mac80211/iface.c:1426 [inline]
 ieee80211_iface_work+0x7f7/0xa40 net/mac80211/iface.c:1462
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3594
 cfg80211_update_known_bss+0x833/0xa60 net/wireless/scan.c:1661
 cfg80211_bss_update+0xef/0x1e10 net/wireless/scan.c:1708
 cfg80211_inform_single_bss_frame_data+0x6e8/0xee0 net/wireless/scan.c:2414
 cfg80211_inform_bss_frame_data+0xa7/0xb10 net/wireless/scan.c:2447
 ieee80211_bss_info_update+0x374/0xb70 net/mac80211/scan.c:190
 ieee80211_rx_bss_info net/mac80211/ibss.c:1126 [inline]
 ieee80211_rx_mgmt_probe_beacon+0xcc6/0x17c0 net/mac80211/ibss.c:1615
 ieee80211_ibss_rx_queued_mgmt+0xd30/0x1610 net/mac80211/ibss.c:1642
 ieee80211_iface_process_skb net/mac80211/iface.c:1426 [inline]
 ieee80211_iface_work+0x7f7/0xa40 net/mac80211/iface.c:1462
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888021a03080
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 28 bytes inside of
 96-byte region [ffff888021a03080, ffff888021a030e0)
The buggy address belongs to the page:
page:ffffea00008680c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888021a03f80 pfn:0x21a03
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000b7b0c0 0000001d0000001d ffff888010841780
raw: ffff888021a03f80 0000000080200015 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 2958, ts 186936087381, free_ts 183095161487
 prep_new_page mm/page_alloc.c:2433 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5374
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
 alloc_slab_page mm/slub.c:1713 [inline]
 allocate_slab+0x32b/0x4c0 mm/slub.c:1853
 new_slab mm/slub.c:1916 [inline]
 new_slab_objects mm/slub.c:2662 [inline]
 ___slab_alloc+0x4ba/0x820 mm/slub.c:2825
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2865
 slab_alloc_node mm/slub.c:2947 [inline]
 slab_alloc mm/slub.c:2989 [inline]
 kmem_cache_alloc_trace+0x30f/0x3c0 mm/slub.c:3006
 kmalloc include/linux/slab.h:591 [inline]
 dst_cow_metrics_generic+0x48/0x1e0 net/core/dst.c:201
 dst_metrics_write_ptr include/net/dst.h:118 [inline]
 dst_metric_set include/net/dst.h:179 [inline]
 icmp6_dst_alloc+0x4f5/0x6c0 net/ipv6/route.c:3291
 mld_sendpack+0x586/0xdc0 net/ipv6/mcast.c:1812
 mld_send_initial_cr.part.0+0x194/0x230 net/ipv6/mcast.c:2242
 mld_send_initial_cr net/ipv6/mcast.c:1227 [inline]
 ipv6_mc_dad_complete+0x1d0/0x690 net/ipv6/mcast.c:2250
 addrconf_dad_completed+0xa20/0xd60 net/ipv6/addrconf.c:4175
 addrconf_dad_work+0x79f/0x1340 net/ipv6/addrconf.c:4105
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1343 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1394
 free_unref_page_prepare mm/page_alloc.c:3329 [inline]
 free_unref_page_list+0x1a1/0x1050 mm/page_alloc.c:3445
 release_pages+0x824/0x20b0 mm/swap.c:972
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
 tlb_flush_mmu mm/mmu_gather.c:249 [inline]
 tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:340
 exit_mmap+0x1ea/0x620 mm/mmap.c:3203
 __mmput+0x122/0x470 kernel/fork.c:1101
 mmput+0x58/0x60 kernel/fork.c:1122
 exit_mm kernel/exit.c:501 [inline]
 do_exit+0xae2/0x2a60 kernel/exit.c:812
 do_group_exit+0x125/0x310 kernel/exit.c:922
 __do_sys_exit_group kernel/exit.c:933 [inline]
 __se_sys_exit_group kernel/exit.c:931 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888021a02f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888021a03000: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888021a03080: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                            ^
 ffff888021a03100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888021a03180: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
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