================================================================== BUG: KASAN: use-after-free in strlen+0x79/0x90 lib/string.c:527 Read of size 1 at addr ffff8881aec07208 by task syz-executor.3/1273 CPU: 1 PID: 1273 Comm: syz-executor.3 Not tainted 5.5.0-rc2-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+0xef/0x16e lib/dump_stack.c:118 print_address_description.constprop.0+0x16/0x200 mm/kasan/report.c:374 __kasan_report.cold+0x37/0x7f mm/kasan/report.c:506 kasan_report+0xe/0x20 mm/kasan/common.c:639 strlen+0x79/0x90 lib/string.c:527 strlen include/linux/string.h:302 [inline] str_to_user+0x27/0x90 drivers/input/evdev.c:783 evdev_do_ioctl drivers/input/evdev.c:1186 [inline] evdev_ioctl_handler+0x130a/0x19f0 drivers/input/evdev.c:1284 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x90c/0x1420 fs/ioctl.c:732 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:754 do_syscall_64+0xb6/0x5c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a919 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:00007f548d327c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919 RDX: 0000000020000280 RSI: 0000000080404507 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f548d3286d4 R13: 00000000004c2e4f R14: 00000000004d8078 R15: 00000000ffffffff Allocated by task 238: save_stack+0x1b/0x80 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+0xbf/0xd0 mm/kasan/common.c:486 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2759 [inline] __kmalloc_node_track_caller+0xfc/0x380 mm/slub.c:4365 __kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:141 __alloc_skb+0xef/0x5a0 net/core/skbuff.c:209 alloc_skb include/linux/skbuff.h:1049 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1174 [inline] netlink_sendmsg+0x97b/0xe00 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:639 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:659 ____sys_sendmsg+0x6b9/0x7d0 net/socket.c:2330 ___sys_sendmsg+0x100/0x170 net/socket.c:2384 __sys_sendmsg+0xec/0x1b0 net/socket.c:2417 do_syscall_64+0xb6/0x5c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 26657: save_stack+0x1b/0x80 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+0x129/0x170 mm/kasan/common.c:474 slab_free_hook mm/slub.c:1425 [inline] slab_free_freelist_hook mm/slub.c:1458 [inline] slab_free mm/slub.c:3005 [inline] kfree+0xda/0x310 mm/slub.c:3957 skb_free_head+0x8b/0xa0 net/core/skbuff.c:591 skb_release_data+0x41f/0x7c0 net/core/skbuff.c:611 skb_release_all+0x46/0x60 net/core/skbuff.c:665 __kfree_skb net/core/skbuff.c:679 [inline] consume_skb net/core/skbuff.c:838 [inline] consume_skb+0xd9/0x380 net/core/skbuff.c:832 skb_free_datagram+0x16/0xf0 net/core/datagram.c:328 netlink_recvmsg+0x65e/0xee0 net/netlink/af_netlink.c:1996 sock_recvmsg_nosec net/socket.c:873 [inline] sock_recvmsg net/socket.c:891 [inline] sock_recvmsg+0xca/0x110 net/socket.c:887 ____sys_recvmsg+0x202/0x580 net/socket.c:2553 ___sys_recvmsg+0xe4/0x150 net/socket.c:2595 __sys_recvmsg+0xe9/0x1b0 net/socket.c:2629 do_syscall_64+0xb6/0x5c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881aec07000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 520 bytes inside of 1024-byte region [ffff8881aec07000, ffff8881aec07400) The buggy address belongs to the page: page:ffffea0006bb0000 refcount:1 mapcount:0 mapping:ffff8881da002280 index:0x0 compound_mapcount: 0 raw: 0200000000010200 ffffea0006b36200 0000000300000003 ffff8881da002280 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881aec07100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881aec07180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881aec07200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881aec07280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881aec07300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================