================================================================== BUG: KASAN: slab-use-after-free in nsproxy_free+0x572/0x5a0 Read of size 8 at addr ffff88800db12861 by task syz-executor.0/4084 CPU: 1 UID: 0 PID: 4084 Comm: syz-executor.0 Not tainted 6.18.0-rc5-next-20251114 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xca/0x120 print_report+0xcb/0x610 kasan_report+0xca/0x100 nsproxy_free+0x572/0x5a0 create_new_namespaces+0x585/0x750 unshare_nsproxy_namespaces+0xc0/0x200 ksys_unshare+0x468/0xa10 __x64_sys_unshare+0x31/0x40 do_syscall_64+0xbf/0x430 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5689fadb19 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5687502188 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f568a0c1020 RCX: 00007f5689fadb19 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000004a000080 RBP: 00007f568a007f6d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff664965bf R14: 00007f5687502300 R15: 0000000000022000 Allocated by task 4084: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 __kmalloc_node_track_caller_noprof+0x2c0/0x770 kmemdup_noprof+0x2b/0x60 devinet_init_net+0xc3/0x910 ops_init+0x1e1/0x650 setup_net+0x11b/0x330 copy_net_ns+0x347/0x790 create_new_namespaces+0x3cd/0x750 unshare_nsproxy_namespaces+0xc0/0x200 ksys_unshare+0x468/0xa10 __x64_sys_unshare+0x31/0x40 do_syscall_64+0xbf/0x430 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 4084: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3a/0x60 __kasan_slab_free+0x43/0x70 kfree+0x13c/0x510 devinet_exit_net+0x1e5/0x2c0 ops_undo_list+0x2d5/0xa50 setup_net+0x1c4/0x330 copy_net_ns+0x347/0x790 create_new_namespaces+0x3cd/0x750 unshare_nsproxy_namespaces+0xc0/0x200 ksys_unshare+0x468/0xa10 __x64_sys_unshare+0x31/0x40 do_syscall_64+0xbf/0x430 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800db12800 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 97 bytes inside of freed 192-byte region [ffff88800db12800, ffff88800db128c0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xdb12 anon flags: 0x100000000000000(node=0|zone=1) page_type: f5(slab) raw: 0100000000000000 ffff888008c413c0 ffffea0000374700 dead000000000003 raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88800db12700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800db12780: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc >ffff88800db12800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88800db12880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88800db12900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== Oops: general protection fault, probably for non-canonical address 0xdffffc000000002e: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000170-0x0000000000000177] CPU: 1 UID: 0 PID: 4084 Comm: syz-executor.0 Tainted: G B 6.18.0-rc5-next-20251114 #1 PREEMPT(voluntary) Tainted: [B]=BAD_PAGE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:nsproxy_free+0x28a/0x5a0 Code: 02 00 00 4c 8b 65 28 4d 85 e4 74 43 e8 7f 56 30 00 49 8d bc 24 78 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f7 02 00 00 49 8b 9c 24 78 01 00 00 bf 08 00 00 RSP: 0018:ffff8880490b7dc8 EFLAGS: 00010217 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffc9000d41f000 RDX: 000000000000002e RSI: ffffffff8144dd61 RDI: 0000000000000174 RBP: ffff88800d8f9e38 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff8664ed57 R11: ffff888020662370 R12: fffffffffffffffc R13: ffff88801f54e61c R14: ffffffff85cfdf20 R15: ffff888013792438 FS: 00007f5687502700(0000) GS:ffff8880e548f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc1a830b718 CR3: 000000000cef0000 CR4: 0000000000350ef0 Call Trace: create_new_namespaces+0x585/0x750 unshare_nsproxy_namespaces+0xc0/0x200 ksys_unshare+0x468/0xa10 __x64_sys_unshare+0x31/0x40 do_syscall_64+0xbf/0x430 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5689fadb19 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5687502188 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f568a0c1020 RCX: 00007f5689fadb19 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000004a000080 RBP: 00007f568a007f6d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff664965bf R14: 00007f5687502300 R15: 0000000000022000 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:nsproxy_free+0x28a/0x5a0 Code: 02 00 00 4c 8b 65 28 4d 85 e4 74 43 e8 7f 56 30 00 49 8d bc 24 78 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f7 02 00 00 49 8b 9c 24 78 01 00 00 bf 08 00 00 RSP: 0018:ffff8880490b7dc8 EFLAGS: 00010217 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffc9000d41f000 RDX: 000000000000002e RSI: ffffffff8144dd61 RDI: 0000000000000174 RBP: ffff88800d8f9e38 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff8664ed57 R11: ffff888020662370 R12: fffffffffffffffc R13: ffff88801f54e61c R14: ffffffff85cfdf20 R15: ffff888013792438 FS: 00007f5687502700(0000) GS:ffff8880e548f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc1a830b718 CR3: 000000000cef0000 CR4: 0000000000350ef0 sr 1:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s sr 1:0:0:0: [sr0] tag#0 Sense Key : Not Ready [current] sr 1:0:0:0: [sr0] tag#0 Add. Sense: Medium not present sr 1:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00 I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2 Bluetooth: hci7: link tx timeout Bluetooth: hci7: killing stalled connection 11:aa:aa:aa:aa:aa Bluetooth: hci7: link tx timeout Bluetooth: hci7: killing stalled connection 11:aa:aa:aa:aa:aa Process accounting resumed Bluetooth: hci7: command 0x0406 tx timeout sr 1:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s sr 1:0:0:0: [sr0] tag#0 Sense Key : Not Ready [current] sr 1:0:0:0: [sr0] tag#0 Add. Sense: Medium not present sr 1:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00 I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2 vfat: Unknown parameter 'nnonumtail' vfat: Unknown parameter 'nnonumtail' mac80211_hwsim: wmediumd released netlink socket, switching to perfect channel medium loop6: detected capacity change from 0 to 5408 vfat: Unknown parameter '¦ö…:*3‚þ«<ëâ ÿÎ8|X^cv§ÖyÍ\CR;[6Ð|sš”Y¥ˆÎ 'dy ›mYÚh£ôP6íƒ8’ŠºŒ\³¼' loop6: detected capacity change from 0 to 5408 vfat: Unknown parameter '¦ö…:*3‚þ«<ëâ ÿÎ8|X^cv§ÖyÍ\CR;[6Ð|sš”Y¥ˆÎ 'dy ›mYÚh£ôP6íƒ8’ŠºŒ\³¼' mac80211_hwsim: wmediumd released netlink socket, switching to perfect channel medium ---------------- Code disassembly (best guess): 0: 02 00 add (%rax),%al 2: 00 4c 8b 65 add %cl,0x65(%rbx,%rcx,4) 6: 28 4d 85 sub %cl,-0x7b(%rbp) 9: e4 74 in $0x74,%al b: 43 e8 7f 56 30 00 rex.XB callq 0x305690 11: 49 8d bc 24 78 01 00 lea 0x178(%r12),%rdi 18: 00 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 0f 85 f7 02 00 00 jne 0x32b 34: 49 8b 9c 24 78 01 00 mov 0x178(%r12),%rbx 3b: 00 3c: bf .byte 0xbf 3d: 08 00 or %al,(%rax)