bisecting cause commit starting from 770fbb32d34e5d6298cc2be590c9d2fd6069aa17 building syzkaller on 05736b290dd5af17adbb0fb5ea67405a0167a7c8 testing commit 770fbb32d34e5d6298cc2be590c9d2fd6069aa17 with gcc (GCC) 8.1.0 kernel signature: 1523628ab60165fe55f9c500e249054f235bb1a00ed9530f857da94a12750991 run #0: crashed: general protection fault in try_to_wake_up run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: slab-out-of-bounds Write in tcindex_set_parms run #3: crashed: KASAN: use-after-free Write in tcindex_set_parms run #4: crashed: KASAN: invalid-free in tcf_exts_destroy run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: KASAN: use-after-free Write in tcindex_set_parms run #7: crashed: KASAN: invalid-free in tcf_exts_destroy run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: general protection fault in tcf_action_destroy testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.1.0 kernel signature: 84019f8557797fbf50c02745b6a2ff5540a7f9312bf419be20e26aeb982f0cf9 all runs: OK # git bisect start 770fbb32d34e5d6298cc2be590c9d2fd6069aa17 d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 Bisecting: 8851 revisions left to test after this (roughly 13 steps) [f8f0d0b6fa203bfa363d30f34f6fecce9e5cc2f7] mm: ptdump: reduce level numbers by 1 in note_page() testing commit f8f0d0b6fa203bfa363d30f34f6fecce9e5cc2f7 with gcc (GCC) 8.1.0 kernel signature: a635e49222c727e04c8ace9dc922ffa876fff7305fa17e1685d656255ceeb056 all runs: OK # git bisect good f8f0d0b6fa203bfa363d30f34f6fecce9e5cc2f7 Bisecting: 4440 revisions left to test after this (roughly 12 steps) [f3c8aeba659078b44a0a5080c3690ac07f2433bc] Merge remote-tracking branch 'sh/sh-next' testing commit f3c8aeba659078b44a0a5080c3690ac07f2433bc with gcc (GCC) 8.1.0 kernel signature: 595cabd1ac9da67d193f3aebd4b9acda578d1aed1c8214f5dd438a8a6136890d run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: general protection fault in tcf_action_destroy run #4: crashed: general protection fault in tcf_action_destroy run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: general protection fault in tcf_action_destroy run #7: crashed: KASAN: use-after-free Write in tcindex_set_parms run #8: crashed: WARNING: refcount bug in __tcf_action_put run #9: crashed: KASAN: invalid-free in tcf_exts_destroy # git bisect bad f3c8aeba659078b44a0a5080c3690ac07f2433bc Bisecting: 2253 revisions left to test after this (roughly 11 steps) [1afa9c3b7c9bdcb562e2afe9f58cc99d0b071cdc] Merge tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc testing commit 1afa9c3b7c9bdcb562e2afe9f58cc99d0b071cdc with gcc (GCC) 8.1.0 kernel signature: b62480f06cf5452860193ea9d354c217732ff13c5bffc112dc402b5eabbd491b run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: general protection fault in tcf_action_destroy run #2: crashed: KASAN: slab-out-of-bounds Write in tcindex_set_parms run #3: crashed: WARNING in tcf_exts_destroy run #4: crashed: general protection fault in tcf_action_destroy run #5: crashed: KASAN: use-after-free Write in tcindex_set_parms run #6: crashed: KASAN: use-after-free Write in tcindex_set_parms run #7: crashed: KASAN: use-after-free Write in tcindex_set_parms run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: KASAN: use-after-free Write in tcindex_set_parms # git bisect bad 1afa9c3b7c9bdcb562e2afe9f58cc99d0b071cdc Bisecting: 1037 revisions left to test after this (roughly 10 steps) [c16b99d6c5a3f103ae45e33084055a2440d70544] Merge tag 'drm-next-2020-02-07' of git://anongit.freedesktop.org/drm/drm testing commit c16b99d6c5a3f103ae45e33084055a2440d70544 with gcc (GCC) 8.1.0 kernel signature: fa464ce1cd0decdfcf3746067263feda0c6e5a4307fae1ea34de3ef4cac4bff1 run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: general protection fault in tcf_action_destroy run #4: crashed: WARNING in tcf_exts_destroy run #5: crashed: KASAN: use-after-free Write in tcindex_set_parms run #6: crashed: KASAN: use-after-free Write in tcindex_set_parms run #7: crashed: general protection fault in tcf_action_destroy run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: general protection fault in tcf_action_destroy # git bisect bad c16b99d6c5a3f103ae45e33084055a2440d70544 Bisecting: 556 revisions left to test after this (roughly 9 steps) [cfb4b571e8b56b65d1a893bda5153647fda823b9] Merge tag 's390-5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux testing commit cfb4b571e8b56b65d1a893bda5153647fda823b9 with gcc (GCC) 8.1.0 kernel signature: f1d11bd15310c088db9f44696f6d416e7e2ad702dcf285a7a494f51f7516fc79 run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: general protection fault in tcf_action_destroy run #4: crashed: KASAN: use-after-free Write in tcindex_set_parms run #5: crashed: KASAN: use-after-free Write in tcindex_set_parms run #6: crashed: KASAN: use-after-free Write in tcindex_set_parms run #7: crashed: KASAN: use-after-free Write in tcindex_set_parms run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: KASAN: use-after-free Write in tcindex_set_parms # git bisect bad cfb4b571e8b56b65d1a893bda5153647fda823b9 Bisecting: 276 revisions left to test after this (roughly 8 steps) [cc12071ff39060fc2e47c58b43e249fe0d0061ee] Merge branch 'akpm' (patches from Andrew) testing commit cc12071ff39060fc2e47c58b43e249fe0d0061ee with gcc (GCC) 8.1.0 kernel signature: 9361f53511954ff9ab9c06d7e4f7e7bec8dfe8df75964619d39749183a7110cc all runs: OK # git bisect good cc12071ff39060fc2e47c58b43e249fe0d0061ee Bisecting: 144 revisions left to test after this (roughly 7 steps) [4c25df5640ae6e4491ee2c50d3f70c1559ef037d] Merge branch 'topic/user-access-begin' into next testing commit 4c25df5640ae6e4491ee2c50d3f70c1559ef037d with gcc (GCC) 8.1.0 kernel signature: 773234cafdc97d5cc059eb8989a3e69e985b3be3493fb0cbd65a079092b5b2bd all runs: OK # git bisect good 4c25df5640ae6e4491ee2c50d3f70c1559ef037d Bisecting: 79 revisions left to test after this (roughly 6 steps) [d60ddd244215da7c695cba858427094d8e366aa7] Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm testing commit d60ddd244215da7c695cba858427094d8e366aa7 with gcc (GCC) 8.1.0 kernel signature: bd73e23b27aef50083d034814d37159327cd1bea6bd1c68dbefd73b5327d45f9 all runs: OK # git bisect good d60ddd244215da7c695cba858427094d8e366aa7 Bisecting: 39 revisions left to test after this (roughly 5 steps) [6556ff32f12d0a5380dd2fa6bbaa01373925a7d1] netdevsim: use IS_ERR instead of IS_ERR_OR_NULL for debugfs testing commit 6556ff32f12d0a5380dd2fa6bbaa01373925a7d1 with gcc (GCC) 8.1.0 kernel signature: 30a13d0e0fe4d56e4fc3a8be6499b5cabb1213e2dc08231dcd92ae1a2f2b2cce all runs: OK # git bisect good 6556ff32f12d0a5380dd2fa6bbaa01373925a7d1 Bisecting: 17 revisions left to test after this (roughly 4 steps) [bddea11b1b9385f713006820f16a9fbe5efe6b47] Merge branch 'imm.timestamp' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs testing commit bddea11b1b9385f713006820f16a9fbe5efe6b47 with gcc (GCC) 8.1.0 kernel signature: dbe669f5862428da044271a8a655713a6d44783b8c75603667059d1d8faf3d47 run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: general protection fault in tcf_action_destroy run #3: crashed: general protection fault in wq_worker_running run #4: crashed: general protection fault in tcf_action_destroy run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: general protection fault in tcf_action_destroy run #7: crashed: general protection fault in tcf_action_destroy run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: KASAN: use-after-free Write in tcindex_set_parms # git bisect bad bddea11b1b9385f713006820f16a9fbe5efe6b47 Bisecting: 10 revisions left to test after this (roughly 4 steps) [0d0d9a388a858e271bb70e71e99e7fe2a6fd6f64] l2tp: Allow duplicate session creation with UDP testing commit 0d0d9a388a858e271bb70e71e99e7fe2a6fd6f64 with gcc (GCC) 8.1.0 kernel signature: c232646e566971e289ebb5f20c1d27e975a87d841c8242e365ef1c35b7288ae4 run #0: crashed: KASAN: use-after-free Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: general protection fault in tcf_action_destroy run #4: crashed: KASAN: use-after-free Write in tcindex_set_parms run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: KASAN: invalid-free in tcf_exts_destroy run #7: crashed: WARNING in tcf_exts_destroy run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: general protection fault in tcf_action_destroy # git bisect bad 0d0d9a388a858e271bb70e71e99e7fe2a6fd6f64 Bisecting: 5 revisions left to test after this (roughly 3 steps) [7145fcfffef1fad4266aaf5ca96727696916edb7] tc-testing: fix eBPF tests failure on linux fresh clones testing commit 7145fcfffef1fad4266aaf5ca96727696916edb7 with gcc (GCC) 8.1.0 kernel signature: c907befd28df1f450d1229fa120b7f55493f15220eb7e03734de64596930249a all runs: OK # git bisect good 7145fcfffef1fad4266aaf5ca96727696916edb7 Bisecting: 2 revisions left to test after this (roughly 2 steps) [83b43045308ea0600099830292955f18818f8d5e] qed: Remove set but not used variable 'p_link' testing commit 83b43045308ea0600099830292955f18818f8d5e with gcc (GCC) 8.1.0 kernel signature: d9ac4f265be1f55b34d6ef5e1936180073f81ed1a3ebab864a832c12eafa744b all runs: OK # git bisect good 83b43045308ea0600099830292955f18818f8d5e Bisecting: 0 revisions left to test after this (roughly 1 step) [b4b771fd51fda70577dc980429347c41e807c64f] r8152: Add MAC passthrough support to new device testing commit b4b771fd51fda70577dc980429347c41e807c64f with gcc (GCC) 8.1.0 kernel signature: a5baaf132ae87c6d5470151f38c73f22b69bca77bfbf28061dde54aaeae90b3a run #0: crashed: KASAN: slab-out-of-bounds Write in tcindex_set_parms run #1: crashed: KASAN: use-after-free Write in tcindex_set_parms run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: general protection fault in tcf_action_destroy run #4: crashed: KASAN: use-after-free Write in tcindex_set_parms run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: general protection fault in tcf_action_destroy run #7: crashed: KASAN: use-after-free Write in tcindex_set_parms run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: general protection fault in tcf_action_destroy # git bisect bad b4b771fd51fda70577dc980429347c41e807c64f Bisecting: 0 revisions left to test after this (roughly 0 steps) [599be01ee567b61f4471ee8078870847d0a11e8e] net_sched: fix an OOB access in cls_tcindex testing commit 599be01ee567b61f4471ee8078870847d0a11e8e with gcc (GCC) 8.1.0 kernel signature: 2d8dc13b6579eb90604816ddcedbdf4ec24a4d04fc1bd611c299cd1c131da208 run #0: crashed: general protection fault in tcf_action_destroy run #1: crashed: general protection fault in tcf_action_destroy run #2: crashed: KASAN: use-after-free Write in tcindex_set_parms run #3: crashed: KASAN: use-after-free Write in tcindex_set_parms run #4: crashed: KASAN: use-after-free Write in tcindex_set_parms run #5: crashed: general protection fault in tcf_action_destroy run #6: crashed: KASAN: use-after-free Write in tcindex_set_parms run #7: crashed: general protection fault in tcf_action_destroy run #8: crashed: KASAN: use-after-free Write in tcindex_set_parms run #9: crashed: KASAN: invalid-free in tcf_exts_destroy # git bisect bad 599be01ee567b61f4471ee8078870847d0a11e8e 599be01ee567b61f4471ee8078870847d0a11e8e is the first bad commit commit 599be01ee567b61f4471ee8078870847d0a11e8e Author: Cong Wang Date: Sun Feb 2 21:14:35 2020 -0800 net_sched: fix an OOB access in cls_tcindex As Eric noticed, tcindex_alloc_perfect_hash() uses cp->hash to compute the size of memory allocation, but cp->hash is set again after the allocation, this caused an out-of-bound access. So we have to move all cp->hash initialization and computation before the memory allocation. Move cp->mask and cp->shift together as cp->hash may need them for computation too. Reported-and-tested-by: syzbot+35d4dea36c387813ed31@syzkaller.appspotmail.com Fixes: 331b72922c5f ("net: sched: RCU cls_tcindex") Cc: Eric Dumazet Cc: John Fastabend Cc: Jamal Hadi Salim Cc: Jiri Pirko Cc: Jakub Kicinski Signed-off-by: Cong Wang Signed-off-by: David S. Miller net/sched/cls_tcindex.c | 40 ++++++++++++++++++++-------------------- 1 file changed, 20 insertions(+), 20 deletions(-) culprit signature: 2d8dc13b6579eb90604816ddcedbdf4ec24a4d04fc1bd611c299cd1c131da208 parent signature: d9ac4f265be1f55b34d6ef5e1936180073f81ed1a3ebab864a832c12eafa744b revisions tested: 17, total time: 3h39m18.756384037s (build: 1h46m46.502419698s, test: 1h51m8.93944282s) first bad commit: 599be01ee567b61f4471ee8078870847d0a11e8e net_sched: fix an OOB access in cls_tcindex cc: ["davem@davemloft.net" "syzbot+35d4dea36c387813ed31@syzkaller.appspotmail.com" "xiyou.wangcong@gmail.com"] crash: KASAN: invalid-free in tcf_exts_destroy ================================================================== BUG: KASAN: double-free or invalid-free in tcf_exts_destroy+0x53/0xb0 net/sched/cls_api.c:3002 CPU: 0 PID: 8462 Comm: syz-executor.3 Not tainted 5.5.0-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+0x128/0x182 lib/dump_stack.c:118 print_address_description.constprop.8.cold.10+0x9/0x317 mm/kasan/report.c:374 kasan_report_invalid_free+0x60/0xa0 mm/kasan/report.c:468 __kasan_slab_free+0x129/0x140 mm/kasan/common.c:453 __cache_free mm/slab.c:3426 [inline] kfree+0x107/0x2b0 mm/slab.c:3757 tcf_exts_destroy+0x53/0xb0 net/sched/cls_api.c:3002 tcf_exts_change+0xeb/0x140 net/sched/cls_api.c:3059 tcindex_set_parms+0xcce/0x1b90 net/sched/cls_tcindex.c:456 tcindex_change+0x1c2/0x280 net/sched/cls_tcindex.c:519 tc_new_tfilter+0xffa/0x1da0 net/sched/cls_api.c:2103 rtnetlink_rcv_msg+0x60c/0x8c0 net/core/rtnetlink.c:5429 netlink_rcv_skb+0x119/0x340 net/netlink/af_netlink.c:2477 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0x434/0x630 net/netlink/af_netlink.c:1328 netlink_sendmsg+0x714/0xc60 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xac/0xe0 net/socket.c:672 ____sys_sendmsg+0x54e/0x750 net/socket.c:2343 ___sys_sendmsg+0xe4/0x160 net/socket.c:2397 __sys_sendmsg+0xce/0x170 net/socket.c:2430 do_syscall_64+0xc6/0x5e0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c849 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:00007f66f1bbfc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f66f1bc06d4 RCX: 000000000045c849 RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009fd R14: 00000000004ccb4d R15: 000000000076bf0c Allocated by task 7127: save_stack+0x19/0x80 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc.constprop.17+0xc1/0xd0 mm/kasan/common.c:513 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc_track_caller+0x15c/0x7a0 mm/slab.c:3671 kmemdup+0x17/0x40 mm/util.c:127 kmemdup include/linux/string.h:453 [inline] neigh_parms_alloc+0x7a/0x420 net/core/neighbour.c:1615 ipv6_add_dev+0x287/0xed0 net/ipv6/addrconf.c:387 addrconf_notify+0x4d1/0x1ea0 net/ipv6/addrconf.c:3491 notifier_call_chain+0x86/0x150 kernel/notifier.c:83 call_netdevice_notifiers_extack net/core/dev.c:1955 [inline] call_netdevice_notifiers net/core/dev.c:1969 [inline] register_netdevice+0x60b/0xe30 net/core/dev.c:9411 register_netdev+0x15/0x30 net/core/dev.c:9504 ip6_tnl_init_net+0x420/0x6a0 net/ipv6/ip6_tunnel.c:2242 ops_init+0x92/0x350 net/core/net_namespace.c:137 setup_net+0x2c0/0x780 net/core/net_namespace.c:327 copy_net_ns+0x24d/0x490 net/core/net_namespace.c:468 create_new_namespaces+0x491/0x900 kernel/nsproxy.c:108 unshare_nsproxy_namespaces+0x82/0x1a0 kernel/nsproxy.c:229 ksys_unshare+0x321/0x6a0 kernel/fork.c:2955 __do_sys_unshare kernel/fork.c:3023 [inline] __se_sys_unshare kernel/fork.c:3021 [inline] __x64_sys_unshare+0x28/0x40 kernel/fork.c:3021 do_syscall_64+0xc6/0x5e0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 1: save_stack+0x19/0x80 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+0xf7/0x140 mm/kasan/common.c:474 __cache_free mm/slab.c:3426 [inline] kfree+0x107/0x2b0 mm/slab.c:3757 usb_start_wait_urb+0x194/0x260 drivers/usb/core/message.c:79 usb_internal_control_msg drivers/usb/core/message.c:101 [inline] usb_control_msg+0x305/0x4d0 drivers/usb/core/message.c:152 usb_get_string+0x94/0x120 drivers/usb/core/message.c:693 usb_string_sub+0xaa/0x380 drivers/usb/core/message.c:732 usb_string+0x27e/0x3d0 drivers/usb/core/message.c:836 usb_cache_string+0x5f/0xc0 drivers/usb/core/message.c:878 usb_enumerate_device drivers/usb/core/hub.c:2382 [inline] usb_new_device+0x1ae/0x6d0 drivers/usb/core/hub.c:2507 register_root_hub drivers/usb/core/hcd.c:1008 [inline] usb_add_hcd.cold.50+0xedd/0x11d9 drivers/usb/core/hcd.c:2790 dummy_hcd_probe+0x155/0x26c drivers/usb/gadget/udc/dummy_hcd.c:2639 platform_drv_probe+0x6b/0xf0 drivers/base/platform.c:727 really_probe+0x1f9/0x5e0 drivers/base/dd.c:551 driver_probe_device+0xc9/0x1b0 drivers/base/dd.c:724 bus_for_each_drv+0x117/0x1a0 drivers/base/bus.c:431 __device_attach+0x1be/0x2c0 drivers/base/dd.c:897 bus_probe_device+0x19e/0x250 drivers/base/bus.c:491 device_add+0x10d0/0x1900 drivers/base/core.c:2487 platform_device_add+0x2ad/0x5b0 drivers/base/platform.c:564 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline] init+0x3a3/0x767 arch/x86/crypto/chacha_glue.c:299 do_one_initcall+0xc3/0x580 init/main.c:939 do_initcall_level init/main.c:1007 [inline] do_initcalls init/main.c:1015 [inline] do_basic_setup init/main.c:1032 [inline] kernel_init_freeable+0x44d/0x4b9 init/main.c:1203 kernel_init+0x7/0x102 init/main.c:1110 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff88809efc5900 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 16 bytes inside of 192-byte region [ffff88809efc5900, ffff88809efc59c0) The buggy address belongs to the page: page:ffffea00027bf140 refcount:1 mapcount:0 mapping:ffff8880aa400000 index:0x0 raw: 00fffe0000000200 ffffea00027bee88 ffffea00027a5688 ffff8880aa400000 raw: 0000000000000000 ffff88809efc5000 0000000100000010 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809efc5800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88809efc5880: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88809efc5900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^ ffff88809efc5980: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88809efc5a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================