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Fri, 26 Jun 2026 14:27:00 -0700 (PDT) Message-ID: <6a3eeea4.3bd3798c.41f1c.06f6@mx.google.com> Date: Fri, 26 Jun 2026 14:27:00 -0700 (PDT) Subject: KASAN: slab-use-after-free Read in jfs_lazycommit To: shaggy@kernel.org, brauner@kernel.org, mjguzik@gmail.com, ssrane_b23@ee.vjti.ac.in, jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org Cc: syzkaller@googlegroups.com, contact@pgazz.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: sanan.hasanou@gmail.com Good day, dear maintainers, We found a bug using a modified version of syzkaller. Kernel Branch: 7.0-rc1 Kernel Config: Unfortunately, we don't have any reproducer for this bug yet. Thank you! Best regards, Sanan Hasanov ================================================================== BUG: KASAN: slab-use-after-free in jfs_lazycommit+0x74b/0xa90 fs/jfs/jfs_txnmgr.c:2737 Read of size 4 at addr ffff88806b71e894 by task jfsCommit/112 CPU: 1 UID: 0 PID: 112 Comm: jfsCommit Tainted: G L 7.0.0-rc1 #1 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 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 jfs_lazycommit+0x74b/0xa90 fs/jfs/jfs_txnmgr.c:2737 kthread+0x389/0x480 kernel/kthread.c:467 ret_from_fork+0x507/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:245 Allocated by task 32010: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x70 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xa0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x325/0x680 mm/slub.c:5339 kmalloc_noprof include/linux/slab.h:962 [inline] kzalloc_noprof include/linux/slab.h:1200 [inline] jfs_fill_super+0xc2/0xd80 fs/jfs/super.c:452 get_tree_bdev_flags+0x402/0x4c0 fs/super.c:1694 vfs_get_tree+0x8c/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3760 [inline] do_new_mount+0x31a/0xce0 fs/namespace.c:3836 do_mount fs/namespace.c:4159 [inline] __do_sys_mount fs/namespace.c:4348 [inline] __se_sys_mount+0x313/0x400 fs/namespace.c:4325 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x160/0xfc0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 23283: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x70 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2687 [inline] slab_free mm/slub.c:6124 [inline] kfree+0x1c5/0x640 mm/slub.c:6442 generic_shutdown_super+0x137/0x2c0 fs/super.c:646 kill_block_super+0x44/0x90 fs/super.c:1725 deactivate_locked_super+0xb6/0x120 fs/super.c:476 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312 task_work_run+0x1ce/0x250 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0xef/0x4e0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x33b/0xfc0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x4b/0x53 The buggy address belongs to the object at ffff88806b71e800 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 148 bytes inside of freed 256-byte region [ffff88806b71e800, ffff88806b71e900) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806b71fc00 pfn:0x6b71e head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x4fff00000000240(workingset|head|node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000240 ffff888018841b40 ffffea00011ed010 ffffea00016dd610 raw: ffff88806b71fc00 000000000010000a 00000000f5000000 0000000000000000 head: 04fff00000000240 ffff888018841b40 ffffea00011ed010 ffffea00016dd610 head: ffff88806b71fc00 000000000010000a 00000000f5000000 0000000000000000 head: 04fff00000000001 ffffea0001adc781 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 30812, tgid 30807 (syz.5.3073), ts 208748051074, free_ts 208732083627 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x238/0x290 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x24e0/0x2570 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3255 [inline] allocate_slab+0x77/0x670 mm/slub.c:3444 new_slab mm/slub.c:3502 [inline] refill_objects+0x33a/0x3d0 mm/slub.c:7134 refill_sheaf mm/slub.c:2804 [inline] __pcs_replace_empty_main+0x2b6/0x620 mm/slub.c:4578 alloc_from_pcs mm/slub.c:4681 [inline] slab_alloc_node mm/slub.c:4815 [inline] __do_kmalloc_node mm/slub.c:5218 [inline] __kmalloc_noprof+0x478/0x770 mm/slub.c:5231 kmalloc_noprof include/linux/slab.h:966 [inline] kzalloc_noprof include/linux/slab.h:1200 [inline] new_dir fs/proc/proc_sysctl.c:966 [inline] get_subdir fs/proc/proc_sysctl.c:1010 [inline] sysctl_mkdir_p fs/proc/proc_sysctl.c:1320 [inline] __register_sysctl_table+0xba1/0x1340 fs/proc/proc_sysctl.c:1395 neigh_sysctl_register+0x9a2/0xa80 net/core/neighbour.c:3922 addrconf_sysctl_register+0xb3/0x1c0 net/ipv6/addrconf.c:7371 ipv6_add_dev+0xd21/0x13a0 net/ipv6/addrconf.c:459 addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3654 notifier_call_chain+0x1b8/0x3f0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline] call_netdevice_notifiers net/core/dev.c:2301 [inline] register_netdevice+0x16f3/0x1ca0 net/core/dev.c:11449 tun_set_iff+0x83f/0xf00 drivers/net/tun.c:2807 __tun_chr_ioctl+0x783/0x1df0 drivers/net/tun.c:3088 page last free pid 30812 tgid 30807 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0xc3e/0xdd0 mm/page_alloc.c:2978 __slab_free+0x25e/0x2b0 mm/slub.c:5532 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4501 [inline] slab_alloc_node mm/slub.c:4830 [inline] __do_kmalloc_node mm/slub.c:5218 [inline] __kmalloc_noprof+0x31b/0x770 mm/slub.c:5231 kmalloc_noprof include/linux/slab.h:966 [inline] sk_prot_alloc+0xe7/0x210 net/core/sock.c:2245 sk_alloc+0x3a/0x380 net/core/sock.c:2301 tun_chr_open+0x7a/0x510 drivers/net/tun.c:3398 misc_open+0x2d8/0x340 drivers/char/misc.c:163 chrdev_open+0x4c8/0x5d0 fs/char_dev.c:411 do_dentry_open+0x77a/0x14d0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x2d02/0x3740 fs/namei.c:4830 do_file_open+0x203/0x440 fs/namei.c:4859 do_sys_openat2+0x105/0x1e0 fs/open.c:1366 Memory state around the buggy address: ffff88806b71e780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b71e800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88806b71e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88806b71e900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b71e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== <<<<<<<<<<<<<<< tail report >>>>>>>>>>>>>>> raw: 04fff00000000240 ffff888018841b40 ffffea00011ed010 ffffea00016dd610 raw: ffff88806b71fc00 000000000010000a 00000000f5000000 0000000000000000 head: 04fff00000000240 ffff888018841b40 ffffea00011ed010 ffffea00016dd610 head: ffff88806b71fc00 000000000010000a 00000000f5000000 0000000000000000 head: 04fff00000000001 ffffea0001adc781 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 30812, tgid 30807 (syz.5.3073), ts 208748051074, free_ts 208732083627 post_alloc_hook+0x238/0x290 get_page_from_freelist+0x24e0/0x2570 __alloc_frozen_pages_noprof+0x181/0x370 allocate_slab+0x77/0x670 refill_objects+0x33a/0x3d0 __pcs_replace_empty_main+0x2b6/0x620 __kmalloc_noprof+0x478/0x770 __register_sysctl_table+0xba1/0x1340 neigh_sysctl_register+0x9a2/0xa80 addrconf_sysctl_register+0xb3/0x1c0 ipv6_add_dev+0xd21/0x13a0 addrconf_notify+0x771/0x1050 notifier_call_chain+0x1b8/0x3f0 register_netdevice+0x16f3/0x1ca0 tun_set_iff+0x83f/0xf00 __tun_chr_ioctl+0x783/0x1df0 page last free pid 30812 tgid 30807 stack trace: __free_frozen_pages+0xc3e/0xdd0 __slab_free+0x25e/0x2b0 qlist_free_all+0x97/0x100 kasan_quarantine_reduce+0x143/0x160 __kasan_slab_alloc+0x22/0x80 __kmalloc_noprof+0x31b/0x770 sk_prot_alloc+0xe7/0x210 sk_alloc+0x3a/0x380 tun_chr_open+0x7a/0x510 misc_open+0x2d8/0x340 chrdev_open+0x4c8/0x5d0 do_dentry_open+0x77a/0x14d0 vfs_open+0x3b/0x340 path_openat+0x2d02/0x3740 do_file_open+0x203/0x440 do_sys_openat2+0x105/0x1e0 Memory state around the buggy address: ffff88806b71e780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b71e800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88806b71e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88806b71e900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b71e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Kernel panic - not syncing: KASAN: panic_on_warn set ... CPU: 1 UID: 0 PID: 112 Comm: jfsCommit Tainted: G L 7.0.0-rc1 #1 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: vpanic+0x41f/0xa20 panic+0xb9/0xc0 check_panic_on_warn+0x84/0xa0 end_report+0x73/0x180 kasan_report+0x129/0x150 jfs_lazycommit+0x74b/0xa90 kthread+0x389/0x480 ret_from_fork+0x507/0xb90 ret_from_fork_asm+0x11/0x20 Kernel Offset: disabled Rebooting in 86400 seconds.. <<<<<<<<<<<<<<< tail report >>>>>>>>>>>>>>>