Hello, syzbot found the following issue on:
HEAD commit: 7d68e382 bpf: Permit size-0 datasec git tree: bpf-next console output: https://syzkaller.appspot.com/x/log.txt?x=17e024c8d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=e0c7843b8af99dff dashboard link: https://syzkaller.appspot.com/bug?extid=3d1c772efafd3c38d007 compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3d1c772efafd3c38d...@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in rxrpc_get_skb+0x1ce/0x1e0 net/rxrpc/skbuff.c:50 Read of size 1 at addr ffff8880117ae8ed by task kworker/1:4/9736 CPU: 1 PID: 9736 Comm: kworker/1:4 Not tainted 5.11.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: krxrpcd rxrpc_process_call Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230 __kasan_report mm/kasan/report.c:396 [inline] kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413 rxrpc_get_skb+0x1ce/0x1e0 net/rxrpc/skbuff.c:50 rxrpc_resend net/rxrpc/call_event.c:263 [inline] rxrpc_process_call+0x1619/0x1f60 net/rxrpc/call_event.c:412 process_one_work+0x98d/0x15f0 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:296 Allocated by task 20353: 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:401 [inline] ____kasan_kmalloc.constprop.0+0x82/0xa0 mm/kasan/common.c:429 kasan_slab_alloc include/linux/kasan.h:205 [inline] slab_post_alloc_hook mm/slab.h:512 [inline] slab_alloc_node mm/slub.c:2891 [inline] kmem_cache_alloc_node+0x1e0/0x470 mm/slub.c:2927 __alloc_skb+0x71/0x5a0 net/core/skbuff.c:198 alloc_skb include/linux/skbuff.h:1100 [inline] alloc_skb_with_frags+0x93/0x5d0 net/core/skbuff.c:5887 sock_alloc_send_pskb+0x793/0x920 net/core/sock.c:2348 rxrpc_send_data+0xb51/0x2bf0 net/rxrpc/sendmsg.c:358 rxrpc_do_sendmsg+0xc03/0x1350 net/rxrpc/sendmsg.c:744 rxrpc_sendmsg+0x420/0x630 net/rxrpc/af_rxrpc.c:560 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2345 ___sys_sendmsg+0xf3/0x170 net/socket.c:2399 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2432 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 20353: 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:356 ____kasan_slab_free+0xe1/0x110 mm/kasan/common.c:362 kasan_slab_free include/linux/kasan.h:188 [inline] slab_free_hook mm/slub.c:1547 [inline] slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1580 slab_free mm/slub.c:3142 [inline] kmem_cache_free+0x82/0x350 mm/slub.c:3158 kfree_skbmem+0xef/0x1b0 net/core/skbuff.c:633 __kfree_skb net/core/skbuff.c:690 [inline] kfree_skb net/core/skbuff.c:707 [inline] kfree_skb+0x140/0x3f0 net/core/skbuff.c:701 rxrpc_free_skb+0x11d/0x150 net/rxrpc/skbuff.c:78 rxrpc_cleanup_ring net/rxrpc/call_object.c:485 [inline] rxrpc_release_call+0x5dd/0x860 net/rxrpc/call_object.c:552 rxrpc_release_calls_on_socket+0x21c/0x300 net/rxrpc/call_object.c:579 rxrpc_release_sock net/rxrpc/af_rxrpc.c:885 [inline] rxrpc_release+0x263/0x5a0 net/rxrpc/af_rxrpc.c:916 __sock_release+0xcd/0x280 net/socket.c:597 sock_close+0x18/0x20 net/socket.c:1256 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 exit_task_work include/linux/task_work.h:30 [inline] do_exit+0xc5c/0x2ae0 kernel/exit.c:825 do_group_exit+0x125/0x310 kernel/exit.c:922 get_signal+0x3e9/0x20a0 kernel/signal.c:2770 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff8880117ae8c0 which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 45 bytes inside of 232-byte region [ffff8880117ae8c0, ffff8880117ae9a8) The buggy address belongs to the page: page:000000006d18c7f7 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117ae flags: 0xfff00000000200(slab) raw: 00fff00000000200 dead000000000100 dead000000000122 ffff8881406f7c80 raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880117ae780: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880117ae800: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc >ffff8880117ae880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ^ ffff8880117ae900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880117ae980: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc 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