================================================================== BUG: KASAN: slab-use-after-free in kvm_gmem_release+0x179/0x350 virt/kvm/guest_memfd.c:276 Write of size 8 at addr ffff88811e95cd08 by task syz.2.17/3862 CPU: 1 UID: 0 PID: 3862 Comm: syz.2.17 Not tainted syzkaller #0 PREEMPT(none) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0xf4/0x170 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 kvm_gmem_release+0x179/0x350 virt/kvm/guest_memfd.c:276 __fput+0x30b/0x7a0 fs/file_table.c:468 task_work_run+0x149/0x1e0 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xbf/0xd0 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x181/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb383f9efc9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff69fbf7c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fb3841f7da0 RCX: 00007fb383f9efc9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fb3841f7da0 R08: 0000000000000000 R09: 0000000469fbfabf R10: 00007fb3841f7cb0 R11: 0000000000000246 R12: 000000000001233f R13: 00007fff69fbf8c0 R14: ffffffffffffffff R15: 00007fff69fbf8e0 Allocated by task 3863: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x220/0x410 mm/slub.c:4396 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] kvm_set_memory_region+0x54f/0x9c0 virt/kvm/kvm_main.c:2095 kvm_vm_ioctl_set_memory_region+0x51/0xa0 virt/kvm/kvm_main.c:2145 kvm_vm_ioctl+0x302/0x900 virt/kvm/kvm_main.c:5189 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xae/0x100 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x8f/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 3863: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kfree+0x174/0x3e0 mm/slub.c:4879 kvm_set_memory_region+0x754/0x9c0 virt/kvm/kvm_main.c:2121 kvm_vm_ioctl_set_memory_region+0x51/0xa0 virt/kvm/kvm_main.c:2145 kvm_vm_ioctl+0x302/0x900 virt/kvm/kvm_main.c:5189 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xae/0x100 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x8f/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88811e95cc00 which belongs to the cache kmalloc-cg-512 of size 512 The buggy address is located 264 bytes inside of freed 512-byte region [ffff88811e95cc00, ffff88811e95ce00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11e95c head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88811b08a901 flags: 0x200000000000040(head|node=0|zone=2) page_type: f5(slab) raw: 0200000000000040 ffff88810004b140 dead000000000100 dead000000000122 raw: 0000000000000000 0000000080100010 00000000f5000000 ffff88811b08a901 head: 0200000000000040 ffff88810004b140 dead000000000100 dead000000000122 head: 0000000000000000 0000000080100010 00000000f5000000 ffff88811b08a901 head: 0200000000000002 ffffea00047a5701 00000000ffffffff 00000000ffffffff head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2747, tgid 2747 (dhcpcd-run-hook), ts 22234772235, free_ts 13339315646 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x168/0x1a0 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x290d/0x29e0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x26b/0x460 mm/page_alloc.c:5148 alloc_pages_mpol+0xcb/0x270 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:2487 [inline] allocate_slab+0x8a/0x320 mm/slub.c:2655 new_slab mm/slub.c:2709 [inline] ___slab_alloc+0x9c6/0x10a0 mm/slub.c:3891 __slab_alloc mm/slub.c:3981 [inline] __slab_alloc_node mm/slub.c:4056 [inline] slab_alloc_node mm/slub.c:4217 [inline] __kmalloc_cache_noprof+0x27c/0x410 mm/slub.c:4391 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] alloc_pipe_info+0xc9/0x3f0 fs/pipe.c:798 get_pipe_inode fs/pipe.c:894 [inline] create_pipe_files+0x88/0x730 fs/pipe.c:926 __do_pipe_flags+0x2c/0x1c0 fs/pipe.c:988 do_pipe2+0xa1/0x150 fs/pipe.c:1036 __do_sys_pipe2 fs/pipe.c:1054 [inline] __se_sys_pipe2 fs/pipe.c:1052 [inline] __x64_sys_pipe2+0x55/0x70 fs/pipe.c:1052 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x8f/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 2440 tgid 2440 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xa32/0xba0 mm/page_alloc.c:2895 __slab_free+0x2c4/0x370 mm/slub.c:4591 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:340 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4180 [inline] slab_alloc_node mm/slub.c:4229 [inline] __kmalloc_cache_noprof+0x1ad/0x410 mm/slub.c:4391 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] kernfs_fop_open+0x349/0xab0 fs/kernfs/file.c:623 do_dentry_open+0x731/0x1060 fs/open.c:965 vfs_open+0x36/0x2b0 fs/open.c:1095 do_open fs/namei.c:3887 [inline] path_openat+0x23e3/0x2bb0 fs/namei.c:4046 do_filp_open+0x1e4/0x3c0 fs/namei.c:4073 do_sys_openat2+0xfa/0x180 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0xf3/0x120 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x8f/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88811e95cc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811e95cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88811e95cd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811e95cd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811e95ce00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================