================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:953 Read of size 4 at addr ffff8880579f7018 by task syz.2.762/7366 CPU: 0 PID: 7366 Comm: syz.2.762 Not tainted 6.1.141-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x220 mm/kasan/report.c:427 kasan_report+0x10b/0x140 mm/kasan/report.c:531 ext4_ext_binsearch fs/ext4/extents.c:837 [inline] ext4_find_extent+0xbcc/0xe00 fs/ext4/extents.c:953 ext4_ext_map_blocks+0x27d/0x66d0 fs/ext4/extents.c:4165 ext4_map_blocks+0x9d1/0x1b60 fs/ext4/inode.c:679 _ext4_get_block+0x1d7/0x4e0 fs/ext4/inode.c:822 ext4_get_block_unwritten+0x2a/0x100 fs/ext4/inode.c:855 __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991 __block_write_begin fs/buffer.c:2041 [inline] block_page_mkwrite+0x2d8/0x5f0 fs/buffer.c:2510 ext4_page_mkwrite+0x3b2/0x10c0 fs/ext4/inode.c:6313 do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3011 do_shared_fault mm/memory.c:4696 [inline] do_fault mm/memory.c:4764 [inline] handle_pte_fault mm/memory.c:5031 [inline] __handle_mm_fault mm/memory.c:5173 [inline] handle_mm_fault+0x1b10/0x3e70 mm/memory.c:5294 do_user_addr_fault+0x51f/0xb10 arch/x86/mm/fault.c:1340 handle_page_fault arch/x86/mm/fault.c:1431 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1487 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166 Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90003227a88 EFLAGS: 00050246 RAX: ffffffff8407c001 RBX: 0000000000000040 RCX: 0000000000000040 RDX: 0000000000000040 RSI: ffffc90003227b20 RDI: 000020000007d000 RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff52000644f6c R10: fffff52000644f6c R11: 1ffff92000644f64 R12: 00007fffffffefc0 R13: 000000007ffb5a80 R14: 000020000007d000 R15: ffffc90003227b20 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline] _copy_to_user+0xea/0x130 lib/usercopy.c:41 copy_to_user include/linux/uaccess.h:169 [inline] rng_dev_read+0x3c5/0x710 drivers/char/hw_random/core.c:267 do_loop_readv_writev fs/read_write.c:-1 [inline] do_iter_read+0x49f/0xb10 fs/read_write.c:798 vfs_readv fs/read_write.c:916 [inline] do_preadv+0x1f6/0x330 fs/read_write.c:1008 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe0dcd8e929 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:00007fe0ddb12038 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00007fe0dcfb5fa0 RCX: 00007fe0dcd8e929 RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000003 RBP: 00007fe0dce10b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fe0dcfb5fa0 R15: 00007fff2c1da4f8 Allocated by task 15: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xae/0x230 mm/slab_common.c:956 kmalloc_reserve net/core/skbuff.c:446 [inline] __alloc_skb+0x22a/0x7e0 net/core/skbuff.c:515 skb_copy+0x139/0x790 net/core/skbuff.c:1732 mac80211_hwsim_tx_frame_no_nl+0xd6e/0x1330 drivers/net/wireless/mac80211_hwsim.c:1724 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/mac80211_hwsim.c:2053 mac80211_hwsim_beacon_tx+0x61e/0xae0 drivers/net/wireless/mac80211_hwsim.c:2116 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:788 ieee80211_iterate_active_interfaces_atomic+0xd7/0x170 net/mac80211/util.c:824 mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2142 __run_hrtimer kernel/time/hrtimer.c:1752 [inline] __hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1816 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1833 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 run_ksoftirqd+0x98/0xf0 kernel/softirq.c:963 smpboot_thread_fn+0x64a/0xa40 kernel/smpboot.c:164 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 The buggy address belongs to the object at ffff8880579f7000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 24 bytes inside of 512-byte region [ffff8880579f7000, ffff8880579f7200) The buggy address belongs to the physical page: page:ffffea00015e7d00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880579f6000 pfn:0x579f4 head:ffffea00015e7d00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea0001f67408 ffffea0001618608 ffff888017441c80 raw: ffff8880579f6000 0000000000100004 00000001ffffffff 0000000000000000 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 4251, tgid 4251 (syz-executor), ts 103452562136, free_ts 39142598852 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614 alloc_slab_page+0x5d/0x160 mm/slub.c:1794 allocate_slab mm/slub.c:1939 [inline] new_slab+0x87/0x2c0 mm/slub.c:1992 ___slab_alloc+0xbc6/0x1220 mm/slub.c:3180 __slab_alloc mm/slub.c:3279 [inline] slab_alloc_node mm/slub.c:3364 [inline] __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3437 __do_kmalloc_node mm/slab_common.c:935 [inline] __kmalloc_node_track_caller+0x9e/0x230 mm/slab_common.c:956 kmalloc_reserve net/core/skbuff.c:446 [inline] __alloc_skb+0x22a/0x7e0 net/core/skbuff.c:515 alloc_skb include/linux/skbuff.h:1271 [inline] nlmsg_new include/net/netlink.h:991 [inline] inet6_netconf_notify_devconf+0x10b/0x1d0 net/ipv6/addrconf.c:582 __addrconf_sysctl_register+0x36c/0x3d0 net/ipv6/addrconf.c:7164 addrconf_sysctl_register+0x15c/0x1b0 net/ipv6/addrconf.c:7201 ipv6_add_dev+0xbe0/0x1120 net/ipv6/addrconf.c:451 addrconf_notify+0x634/0xf40 net/ipv6/addrconf.c:3601 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline] call_netdevice_notifiers net/core/dev.c:2053 [inline] register_netdevice+0x1600/0x1aa0 net/core/dev.c:10225 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1459 [inline] free_pcp_prepare mm/page_alloc.c:1509 [inline] free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479 free_contig_range+0x9d/0x150 mm/page_alloc.c:9574 destroy_args+0xef/0x8bf mm/debug_vm_pgtable.c:1031 debug_vm_pgtable+0x32a/0x37e mm/debug_vm_pgtable.c:1354 do_one_initcall+0x214/0x7a0 init/main.c:1298 do_initcall_level+0x137/0x1e4 init/main.c:1371 do_initcalls+0x4b/0x8a init/main.c:1387 kernel_init_freeable+0x3fa/0x5ac init/main.c:1626 kernel_init+0x19/0x1b0 init/main.c:1514 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff8880579f6f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880579f6f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880579f7000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880579f7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880579f7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: ff c9 dec %ecx 2: 75 f2 jne 0xfffffff6 4: 89 d1 mov %edx,%ecx 6: c1 e9 03 shr $0x3,%ecx 9: 83 e2 07 and $0x7,%edx c: f3 48 a5 rep movsq %ds:(%rsi),%es:(%rdi) f: 89 d1 mov %edx,%ecx 11: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) 13: 31 c0 xor %eax,%eax 15: 0f 01 ca clac 18: c3 ret 19: 8d 0c ca lea (%rdx,%rcx,8),%ecx 1c: 89 ca mov %ecx,%edx 1e: eb 20 jmp 0x40 20: 0f 01 cb stac 23: 83 fa 40 cmp $0x40,%edx 26: 72 38 jb 0x60 28: 89 d1 mov %edx,%ecx * 2a: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction 2c: 31 c0 xor %eax,%eax 2e: 0f 01 ca clac 31: c3 ret 32: 89 ca mov %ecx,%edx 34: eb 0a jmp 0x40 36: 90 nop 37: 90 nop 38: 90 nop 39: 90 nop 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 90 nop 3e: 90 nop 3f: 90 nop