Hello, syzbot found the following crash on: HEAD commit: c11d28ab Add linux-next specific files for 20200522 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=12fc3e72100000 kernel config: https://syzkaller.appspot.com/x/.config?x=3f6dbdea4159fb66 dashboard link: https://syzkaller.appspot.com/bug?extid=478fd0d54412b8759e0d compiler: gcc (GCC) 9.0.0 20181231 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+478fd0d54412b8759e0d@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: use-after-free in ib_uverbs_remove_one+0x411/0x4e0 drivers/infiniband/core/uverbs_main.c:1210 Read of size 4 at addr ffff888096324578 by task syz-executor.2/15847 CPU: 1 PID: 15847 Comm: syz-executor.2 Not tainted 5.7.0-rc6-next-20200522-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+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 ib_uverbs_remove_one+0x411/0x4e0 drivers/infiniband/core/uverbs_main.c:1210 remove_client_context+0xbe/0x110 drivers/infiniband/core/device.c:732 disable_device+0x13b/0x230 drivers/infiniband/core/device.c:1278 __ib_unregister_device+0x91/0x180 drivers/infiniband/core/device.c:1445 ib_unregister_device_and_put+0x57/0x80 drivers/infiniband/core/device.c:1508 nldev_dellink+0x20a/0x310 drivers/infiniband/core/nldev.c:1571 rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:195 [inline] rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline] rdma_nl_rcv+0x586/0x900 drivers/infiniband/core/netlink.c:259 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352 ___sys_sendmsg+0x100/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45ca29 Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fd6764d1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004ffa00 RCX: 000000000045ca29 RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009af R14: 00000000004d61b0 R15: 00007fd6764d26d4 Allocated by task 9061: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc mm/kasan/common.c:494 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] ib_uverbs_add_one+0x80/0x7c0 drivers/infiniband/core/uverbs_main.c:1107 add_client_context+0x400/0x5e0 drivers/infiniband/core/device.c:677 enable_device_and_get+0x1cd/0x3b0 drivers/infiniband/core/device.c:1326 ib_register_device drivers/infiniband/core/device.c:1392 [inline] ib_register_device+0xa12/0xda0 drivers/infiniband/core/device.c:1353 siw_device_register drivers/infiniband/sw/siw/siw_main.c:70 [inline] siw_newlink drivers/infiniband/sw/siw/siw_main.c:565 [inline] siw_newlink+0xd37/0x1240 drivers/infiniband/sw/siw/siw_main.c:542 nldev_newlink+0x29e/0x420 drivers/infiniband/core/nldev.c:1541 rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:195 [inline] rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline] rdma_nl_rcv+0x586/0x900 drivers/infiniband/core/netlink.c:259 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352 ___sys_sendmsg+0x100/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 15847: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x109/0x2b0 mm/slab.c:3757 device_release+0x71/0x200 drivers/base/core.c:1541 kobject_cleanup lib/kobject.c:701 [inline] kobject_release lib/kobject.c:732 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x2f0 lib/kobject.c:749 cdev_device_del+0x69/0x80 fs/char_dev.c:575 ib_uverbs_remove_one+0x31/0x4e0 drivers/infiniband/core/uverbs_main.c:1209 remove_client_context+0xbe/0x110 drivers/infiniband/core/device.c:732 disable_device+0x13b/0x230 drivers/infiniband/core/device.c:1278 __ib_unregister_device+0x91/0x180 drivers/infiniband/core/device.c:1445 ib_unregister_device_and_put+0x57/0x80 drivers/infiniband/core/device.c:1508 nldev_dellink+0x20a/0x310 drivers/infiniband/core/nldev.c:1571 rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:195 [inline] rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline] rdma_nl_rcv+0x586/0x900 drivers/infiniband/core/netlink.c:259 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352 ___sys_sendmsg+0x100/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 The buggy address belongs to the object at ffff888096324000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1400 bytes inside of 4096-byte region [ffff888096324000, ffff888096325000) The buggy address belongs to the page: page:ffffea000258c900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea000258c900 order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea0002429c08 ffffea000173f988 ffff8880aa002000 raw: 0000000000000000 ffff888096324000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888096324400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888096324480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888096324500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888096324580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888096324600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug is generated by a bot. 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