================================================================== BUG: KASAN: use-after-free in tasklet_action+0x29f/0x340 kernel/softirq.c:506 Read of size 8 at addr ffff8880a7c2ce50 by task syz-executor.5/18274 CPU: 0 PID: 18274 Comm: syz-executor.5 Not tainted 4.14.184-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x283 lib/dump_stack.c:58 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393 tasklet_action+0x29f/0x340 kernel/softirq.c:506 __do_softirq+0x254/0x9bf kernel/softirq.c:288 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1016 do_softirq kernel/softirq.c:332 [inline] do_softirq+0xdf/0x170 kernel/softirq.c:319 __local_bh_enable_ip+0x11d/0x160 kernel/softirq.c:185 sock_orphan include/net/sock.h:1712 [inline] bcm_release+0x48b/0x5c0 net/can/bcm.c:1582 __sock_release+0xcd/0x2b0 net/socket.c:602 sock_close+0x15/0x20 net/socket.c:1139 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x416721 RSP: 002b:00007ffe7d262770 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000416721 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000005 RBP: 0000000000000001 R08: 0000000081298de8 R09: 0000000000000000 R10: 00007ffe7d262860 R11: 0000000000000293 R12: 0000000000790ba0 R13: 0000000000108b90 R14: ffffffffffffffff R15: 000000000078bf0c Allocated by task 18277: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x14d/0x3f0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] bcm_tx_setup net/can/bcm.c:952 [inline] bcm_sendmsg+0x219c/0x3770 net/can/bcm.c:1388 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 ___sys_sendmsg+0x70a/0x840 net/socket.c:2062 __sys_sendmsg+0xa3/0x120 net/socket.c:2096 SYSC_sendmsg net/socket.c:2107 [inline] SyS_sendmsg+0x27/0x40 net/socket.c:2103 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 18274: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcb/0x260 mm/slab.c:3815 bcm_release+0xff/0x5c0 net/can/bcm.c:1540 __sock_release+0xcd/0x2b0 net/socket.c:602 sock_close+0x15/0x20 net/socket.c:1139 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8880a7c2cd80 which belongs to the cache kmalloc-1024 of size 1024 The buggy address is located 208 bytes inside of 1024-byte region [ffff8880a7c2cd80, ffff8880a7c2d180) The buggy address belongs to the page: page:ffffea00029f0b00 count:1 mapcount:0 mapping:ffff8880a7c2c000 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffff8880a7c2c000 0000000000000000 0000000100000007 raw: ffffea000231fea0 ffff8880aa801848 ffff8880aa800ac0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a7c2cd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a7c2cd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a7c2ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a7c2ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a7c2cf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================