================================================================== 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 ffff88801d899d1c by task syz-executor.5/16104 CPU: 1 PID: 16104 Comm: syz-executor.5 Not tainted 5.12.0-rc5-next-20210401-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 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:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x466459 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:00007fb39927c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459 RDX: 00000000200000c0 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffdf56f653f R14: 00007fb39927c300 R15: 0000000000022000 Allocated by task 15355: 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:428 [inline] ____kasan_kmalloc mm/kasan/common.c:507 [inline] ____kasan_kmalloc mm/kasan/common.c:466 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516 kmalloc include/linux/slab.h:558 [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:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 16097: 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:357 ____kasan_slab_free mm/kasan/common.c:360 [inline] ____kasan_slab_free mm/kasan/common.c:325 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1593 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1618 slab_free mm/slub.c:3178 [inline] kfree+0xe5/0x7f0 mm/slub.c:4245 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:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 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:345 kvfree_call_rcu+0x74/0x8c0 kernel/rcu/tree.c:3598 cfg80211_update_known_bss+0x833/0xa60 net/wireless/scan.c:1651 cfg80211_bss_update+0xef/0x1c60 net/wireless/scan.c:1698 cfg80211_inform_single_bss_frame_data+0x6e8/0xe90 net/wireless/scan.c:2400 cfg80211_inform_bss_frame_data+0xa7/0xb10 net/wireless/scan.c:2433 ieee80211_bss_info_update+0x3ce/0xb20 net/mac80211/scan.c:190 ieee80211_rx_bss_info net/mac80211/ibss.c:1126 [inline] ieee80211_rx_mgmt_probe_beacon+0xccd/0x16b0 net/mac80211/ibss.c:1615 ieee80211_ibss_rx_queued_mgmt+0xe43/0x1870 net/mac80211/ibss.c:1642 ieee80211_iface_work+0x761/0x9e0 net/mac80211/iface.c:1440 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 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:345 kvfree_call_rcu+0x74/0x8c0 kernel/rcu/tree.c:3598 cfg80211_update_known_bss+0x833/0xa60 net/wireless/scan.c:1651 cfg80211_bss_update+0xef/0x1c60 net/wireless/scan.c:1698 cfg80211_inform_single_bss_frame_data+0x6e8/0xe90 net/wireless/scan.c:2400 cfg80211_inform_bss_frame_data+0xa7/0xb10 net/wireless/scan.c:2433 ieee80211_bss_info_update+0x3ce/0xb20 net/mac80211/scan.c:190 ieee80211_rx_bss_info net/mac80211/ibss.c:1126 [inline] ieee80211_rx_mgmt_probe_beacon+0xccd/0x16b0 net/mac80211/ibss.c:1615 ieee80211_ibss_rx_queued_mgmt+0xe43/0x1870 net/mac80211/ibss.c:1642 ieee80211_iface_work+0x761/0x9e0 net/mac80211/iface.c:1440 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 The buggy address belongs to the object at ffff88801d899d00 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 28 bytes inside of 96-byte region [ffff88801d899d00, ffff88801d899d60) The buggy address belongs to the page: page:ffffea0000762640 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d899 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 0000000000000000 0000001000000001 ffff888010841780 raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88801d899c00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff88801d899c80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff88801d899d00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88801d899d80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff88801d899e00: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc ==================================================================