================================================================== BUG: KASAN: use-after-free in nr_add_node+0x1fa0/0x2150 net/netrom/nr_route.c:248 Read of size 2 at addr ffff0000eea7d132 by task syz.4.7353/20663 CPU: 0 PID: 20663 Comm: syz.4.7353 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x78/0x30c mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xec/0x158 mm/kasan/report.c:451 __asan_report_load2_noabort+0x44/0x50 mm/kasan/report_generic.c:307 nr_add_node+0x1fa0/0x2150 net/netrom/nr_route.c:248 nr_rt_ioctl+0xc38/0xe40 net/netrom/nr_route.c:651 nr_ioctl+0x19c/0x4ac net/netrom/af_netrom.c:1253 sock_do_ioctl+0x100/0x258 net/socket.c:1147 sock_ioctl+0x238/0x860 net/socket.c:1266 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Allocated by task 20644: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc+0xb0/0xf0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:264 [inline] kmem_cache_alloc_trace+0x26c/0x3ec mm/slub.c:3252 kmalloc include/linux/slab.h:607 [inline] nr_add_node+0x758/0x2150 net/netrom/nr_route.c:146 nr_rt_ioctl+0xc38/0xe40 net/netrom/nr_route.c:651 nr_ioctl+0x19c/0x4ac net/netrom/af_netrom.c:1253 sock_do_ioctl+0x100/0x258 net/socket.c:1147 sock_ioctl+0x238/0x860 net/socket.c:1266 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Freed by task 20663: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4c/0x84 mm/kasan/common.c:46 kasan_set_free_info+0x28/0x4c mm/kasan/generic.c:360 ____kasan_slab_free+0x118/0x164 mm/kasan/common.c:366 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1710 [inline] slab_free_freelist_hook+0x128/0x1e4 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kfree+0x16c/0x400 mm/slub.c:4564 nr_neigh_put+0x154/0x1e4 include/net/netrom.h:142 nr_add_node+0x1794/0x2150 net/netrom/nr_route.c:246 nr_rt_ioctl+0xc38/0xe40 net/netrom/nr_route.c:651 nr_ioctl+0x19c/0x4ac net/netrom/af_netrom.c:1253 sock_do_ioctl+0x100/0x258 net/socket.c:1147 sock_ioctl+0x238/0x860 net/socket.c:1266 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 The buggy address belongs to the object at ffff0000eea7d100 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 50 bytes inside of 128-byte region [ffff0000eea7d100, ffff0000eea7d180) The buggy address belongs to the page: page:00000000161cff47 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12ea7d flags: 0x5ffc00000000200(slab|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000000200 0000000000000000 0000000700000001 ffff0000c0002300 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000eea7d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000eea7d080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000eea7d100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000eea7d180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000eea7d200: 05 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Unable to handle kernel paging request at virtual address 0073806f40000a16 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 [0073806f40000a16] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 20663 Comm: syz.4.7353 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 pstate: 02400005 (nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) pc : __hlist_del include/linux/list.h:856 [inline] pc : hlist_del_init include/linux/list.h:884 [inline] pc : __nr_remove_neigh net/netrom/nr_route.c:298 [inline] pc : nr_remove_neigh+0x6c/0xec net/netrom/nr_route.c:308 lr : __hlist_del include/linux/list.h:853 [inline] lr : hlist_del_init include/linux/list.h:884 [inline] lr : __nr_remove_neigh net/netrom/nr_route.c:298 [inline] lr : nr_remove_neigh+0x64/0xec net/netrom/nr_route.c:308 sp : ffff800020487810 x29: ffff800020487810 x28: 0000000000000ffe x27: 1fffe0001db26583 x26: ffff0000ed932c50 x25: 0000000000000000 x24: ffff0000ed932c1f x23: 1fffe0001db26588 x22: dfff800000000000 x21: 0000000000000000 x20: f3a0037a000050b7 x19: ffff0000eea7d100 x18: 0000000000000203 x17: 0000000000000000 x16: ffff8000082d83bc x15: 00000000ffffffff x14: ffff700004090ee4 x13: 1ffff00004090ee4 x12: 0000000000000004 x11: ffffffffffffffff x10: dfff800000000000 x9 : ffff80001af49250 x8 : 1e74006f40000a16 x7 : 0000000000000000 x6 : ffff8000104aeca0 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000104aecd4 x2 : 0000000000000000 x1 : 0000000000000008 x0 : 0000000000000000 Call trace: __hlist_del include/linux/list.h:853 [inline] hlist_del_init include/linux/list.h:884 [inline] __nr_remove_neigh net/netrom/nr_route.c:298 [inline] nr_remove_neigh+0x6c/0xec net/netrom/nr_route.c:308 nr_add_node+0x197c/0x2150 net/netrom/nr_route.c:249 nr_rt_ioctl+0xc38/0xe40 net/netrom/nr_route.c:651 nr_ioctl+0x19c/0x4ac net/netrom/af_netrom.c:1253 sock_do_ioctl+0x100/0x258 net/socket.c:1147 sock_ioctl+0x238/0x860 net/socket.c:1266 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Code: aa1303e0 960e537c d343fe88 f9400275 (38766908) ---[ end trace f351e74493cd20b1 ]--- ---------------- Code disassembly (best guess): 0: aa1303e0 mov x0, x19 4: 960e537c bl 0xfffffffff8394df4 8: d343fe88 lsr x8, x20, #3 c: f9400275 ldr x21, [x19] * 10: 38766908 ldrb w8, [x8, x22] <-- trapping instruction