================================================================== BUG: KASAN: slab-out-of-bounds in fb_pad_unaligned_buffer+0x420/0x500 drivers/video/fbdev/core/fbmem.c:118 Read of size 1 at addr ffff888028e5f334 by task syz.0.2915/15918 CPU: 0 UID: 0 PID: 15918 Comm: syz.0.2915 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 fb_pad_unaligned_buffer+0x420/0x500 drivers/video/fbdev/core/fbmem.c:118 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:129 [inline] bit_putcs+0xa65/0x1bc0 drivers/video/fbdev/core/bitblit.c:204 fbcon_putcs+0x3a6/0x580 drivers/video/fbdev/core/fbcon.c:1320 con_flush drivers/tty/vt/vt.c:2801 [inline] do_con_write+0x2849/0x5210 drivers/tty/vt/vt.c:3227 con_write+0x24/0x40 drivers/tty/vt/vt.c:3565 process_output_block drivers/tty/n_tty.c:561 [inline] n_tty_write+0xd27/0x1200 drivers/tty/n_tty.c:2377 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write+0x559/0xa20 drivers/tty/tty_io.c:1081 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f319018eec9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f319104a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f31903e5fa0 RCX: 00007f319018eec9 RDX: 0000000000001006 RSI: 0000200000002100 RDI: 0000000000000009 RBP: 00007f3190211f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f31903e6038 R14: 00007f31903e5fa0 R15: 00007ffe16b2a028 Allocated by task 7718: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:400 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417 kasan_kmalloc include/linux/kasan.h:262 [inline] __do_kmalloc_node mm/slub.c:5627 [inline] __kmalloc_noprof+0x411/0x7f0 mm/slub.c:5639 kmalloc_noprof include/linux/slab.h:961 [inline] fbcon_set_font+0x54d/0xec0 drivers/video/fbdev/core/fbcon.c:2536 con_font_set drivers/tty/vt/vt.c:4919 [inline] con_font_op+0xc08/0xfd0 drivers/tty/vt/vt.c:4959 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:472 [inline] vt_ioctl+0x1a89/0x1f20 drivers/tty/vt/vt_ioctl.c:743 tty_ioctl+0x929/0xde0 drivers/tty/tty_io.c:2792 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+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888028e5f000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 292 bytes to the right of allocated 528-byte region [ffff888028e5f000, ffff888028e5f210) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888028e5f800 pfn:0x28e58 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 ffff88813fe26dc0 ffffea0001db3e10 ffffea0001e7cc10 raw: ffff888028e5f800 0000000000100004 00000000f5000000 0000000000000000 head: 00fff00000000240 ffff88813fe26dc0 ffffea0001db3e10 ffffea0001e7cc10 head: ffff888028e5f800 0000000000100004 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0000a39601 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5822, tgid 5822 (syz-executor), ts 76590896346, free_ts 58664963412 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850 prep_new_page mm/page_alloc.c:1858 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:3039 [inline] allocate_slab+0x96/0x3a0 mm/slub.c:3212 new_slab mm/slub.c:3266 [inline] ___slab_alloc+0xe94/0x18a0 mm/slub.c:4636 __slab_alloc+0x65/0x100 mm/slub.c:4755 __slab_alloc_node mm/slub.c:4831 [inline] slab_alloc_node mm/slub.c:5253 [inline] __kmalloc_cache_noprof+0x411/0x6f0 mm/slub.c:5743 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] afs_alloc_call+0x79/0x550 fs/afs/rxrpc.c:163 afs_charge_preallocation+0x226/0x4e0 fs/afs/rxrpc.c:747 afs_open_socket+0x302/0x3a0 fs/afs/rxrpc.c:112 afs_net_init+0x67d/0x880 fs/afs/main.c:116 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137 setup_net+0xfe/0x320 net/core/net_namespace.c:445 copy_net_ns+0x34e/0x4e0 net/core/net_namespace.c:580 create_new_namespaces+0x3f3/0x720 kernel/nsproxy.c:110 page last free pid 5667 tgid 5667 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1394 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2906 discard_slab mm/slub.c:3310 [inline] __put_partials+0x146/0x170 mm/slub.c:3857 put_cpu_partial+0x1f2/0x2e0 mm/slub.c:3932 __slab_free+0x2b9/0x390 mm/slub.c:5906 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:352 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4955 [inline] slab_alloc_node mm/slub.c:5265 [inline] kmem_cache_alloc_node_noprof+0x433/0x710 mm/slub.c:5317 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6671 sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2965 unix_dgram_sendmsg+0x461/0x1850 net/unix/af_unix.c:2153 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 sock_write_iter+0x279/0x360 net/socket.c:1195 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 Memory state around the buggy address: ffff888028e5f200: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888028e5f280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888028e5f300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888028e5f380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888028e5f400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================