loop6: detected capacity change from 0 to 264192 ================================================================== BUG: KASAN: slab-use-after-free in vma_multi_allowed+0x172/0x1b0 Read of size 8 at addr ffff88800e4ac418 by task syz-executor.5/13008 CPU: 0 UID: 0 PID: 13008 Comm: syz-executor.5 Not tainted 6.17.0-rc1-next-20250815 #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 vma_multi_allowed+0x172/0x1b0 __do_sys_mremap+0xcb7/0x1410 do_syscall_64+0xbf/0x360 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f62578e1b19 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:00007f6254e57188 EFLAGS: 00000246 ORIG_RAX: 0000000000000019 RAX: ffffffffffffffda RBX: 00007f62579f4f60 RCX: 00007f62578e1b19 RDX: 0000000000001000 RSI: 0000000000001000 RDI: 0000000020871000 RBP: 00007f625793bf6d R08: 0000000020870000 R09: 0000000000000000 R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffce1c1f98f R14: 00007f6254e57300 R15: 0000000000022000 Allocated by task 833: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x59/0x70 kmem_cache_alloc_noprof+0x13c/0x3d0 vm_area_dup+0x25/0x6f0 dup_mmap+0x80d/0x1d10 copy_process+0x6faf/0x73e0 kernel_clone+0xea/0x7f0 __do_sys_clone+0xce/0x120 do_syscall_64+0xbf/0x360 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 112: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3a/0x60 __kasan_slab_free+0x3f/0x50 slab_free_after_rcu_debug+0xd6/0x290 rcu_core+0x7c8/0x1800 handle_softirqs+0x1b1/0x770 __irq_exit_rcu+0xc4/0x100 irq_exit_rcu+0x9/0x20 sysvec_apic_timer_interrupt+0x70/0x80 asm_sysvec_apic_timer_interrupt+0x1a/0x20 Last potentially related work creation: kasan_save_stack+0x24/0x50 kasan_record_aux_stack+0x89/0xa0 kmem_cache_free+0x145/0x460 vms_complete_munmap_vmas+0x549/0x9f0 do_vmi_align_munmap+0x3db/0x550 do_vmi_munmap+0x1eb/0x3c0 do_munmap+0xbd/0x100 mremap_to+0x242/0x450 __do_sys_mremap+0xca2/0x1410 do_syscall_64+0xbf/0x360 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800e4ac3c0 which belongs to the cache vm_area_struct of size 256 The buggy address is located 88 bytes inside of freed 256-byte region [ffff88800e4ac3c0, ffff88800e4ac4c0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xe4ac memcg:ffff88800e495d81 flags: 0x100000000000000(node=0|zone=1) page_type: f5(slab) raw: 0100000000000000 ffff888008fffc80 dead000000000100 dead000000000122 raw: 0000000000000000 00000000000c000c 00000000f5000000 ffff88800e495d81 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88800e4ac300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800e4ac380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff88800e4ac400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88800e4ac480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88800e4ac500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== syz-executor.2: attempt to access beyond end of device loop2: rw=4096, sector=0, nr_sectors = 2 limit=0 EXT4-fs (loop2): unable to read superblock syz-executor.2: attempt to access beyond end of device loop2: rw=4096, sector=0, nr_sectors = 2 limit=0 EXT4-fs (loop2): unable to read superblock syz-executor.2: attempt to access beyond end of device loop2: rw=4096, sector=0, nr_sectors = 2 limit=0 EXT4-fs (loop2): unable to read superblock syz-executor.2: attempt to access beyond end of device loop2: rw=4096, sector=0, nr_sectors = 2 limit=0 EXT4-fs (loop2): unable to read superblock syz-executor.2: attempt to access beyond end of device loop2: rw=4096, sector=0, nr_sectors = 2 limit=0 EXT4-fs (loop2): unable to read superblock audit: type=1400 audit(1755245282.087:23): avc: denied { watch watch_reads } for pid=13230 comm="syz-executor.3" path="/proc/13230/fdinfo" dev="proc" ino=33752 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=dir permissive=1 audit: type=1400 audit(1755245282.560:24): avc: denied { watch_reads } for pid=13311 comm="syz-executor.7" path="/syzkaller-testdir941908661/syzkaller.uyFxx7/503" dev="sda" ino=16047 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=dir permissive=1 SELinux: Context system_u:ob is not valid (left unmapped). audit: type=1400 audit(1755245282.911:25): avc: denied { associate } for pid=13361 comm="syz-executor.6" name="memfd:" dev="tmpfs" ino=1140 scontext=system_u:object_r:unlabeled_t:s0 tcontext=system_u:object_r:tmpfs_t:s0 tclass=filesystem permissive=1 srawcon="system_u:ob"