================================================================== BUG: KASAN: slab-use-after-free in __mutex_lock_common+0x144/0x2678 kernel/locking/mutex.c:577 Read of size 8 at addr ffff0000c1ea8130 by task jffs2_gcd_mtd0/6806 CPU: 0 UID: 0 PID: 6806 Comm: jffs2_gcd_mtd0 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xa8/0x238 mm/kasan/report.c:378 print_report+0x68/0x84 mm/kasan/report.c:482 kasan_report+0xb0/0x110 mm/kasan/report.c:595 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 __mutex_lock_common+0x144/0x2678 kernel/locking/mutex.c:577 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_interruptible_nested+0x2c/0x38 kernel/locking/mutex.c:835 jffs2_garbage_collect_pass+0xa0/0x19c0 fs/jffs2/gc.c:134 jffs2_garbage_collect_thread+0x3c0/0x430 fs/jffs2/background.c:155 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 Allocated by task 6802: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:562 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x2a4/0x3fc mm/slub.c:4407 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] jffs2_init_fs_context+0x58/0xc0 fs/jffs2/super.c:314 alloc_fs_context+0x538/0x76c fs/fs_context.c:318 fs_context_for_mount+0x34/0x44 fs/fs_context.c:332 do_new_mount+0x140/0x7f4 fs/namespace.c:3787 path_mount+0x5b4/0xde0 fs/namespace.c:4123 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount fs/namespace.c:4324 [inline] __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4324 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 Freed by task 6728: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x74/0x98 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kfree+0x17c/0x474 mm/slub.c:4894 jffs2_kill_sb+0x9c/0xb0 fs/jffs2/super.c:351 deactivate_locked_super+0xc4/0x12c fs/super.c:474 deactivate_super+0xe0/0x100 fs/super.c:507 cleanup_mnt+0x31c/0x3ac fs/namespace.c:1375 __cleanup_mnt+0x20/0x30 fs/namespace.c:1382 task_work_run+0x1dc/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xfc/0x168 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:103 [inline] el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:745 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 The buggy address belongs to the object at ffff0000c1ea8000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 304 bytes inside of freed 4096-byte region [ffff0000c1ea8000, ffff0000c1ea9000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101ea8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000040 ffff0000c0002140 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 05ffc00000000040 ffff0000c0002140 dead000000000100 dead000000000122 head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 05ffc00000000003 fffffdffc307aa01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000c1ea8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c1ea8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000c1ea8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000c1ea8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c1ea8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Unable to handle kernel paging request at virtual address 001feafed5204cc8 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [001feafed5204cc8] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] SMP Modules linked in: CPU: 0 UID: 0 PID: 6806 Comm: jffs2_gcd_mtd0 Tainted: G B syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : mtd_get_master include/linux/mtd/mtd.h:405 [inline] pc : mtd_erase+0x94/0x56c drivers/mtd/mtdcore.c:1383 lr : mtd_get_master include/linux/mtd/mtd.h:405 [inline] lr : mtd_erase+0xb0/0x56c drivers/mtd/mtdcore.c:1383 sp : ffff8000a2257780 x29: ffff8000a2257880 x28: ffff0000da382870 x27: ffff8000a2257800 x26: dfff800000000000 x25: ffff70001444af00 x24: dfff800000000000 x23: ffff0000da382878 x22: ffff0000c8ad00c0 x21: ffff0000c9756d00 x20: a90357f6a9026640 x19: a90357f6a9025ff8 x18: 1fffe0003378f088 x17: ffff80008045443c x16: ffff8000802192dc x15: 0000000000000001 x14: 1ffff0001202cd3e x13: 0000000000000000 x12: 0000000000000000 x11: ffff70001202cd3f x10: 0000000000ff0100 x9 : 0000000000000000 x8 : 15206afed5204cc8 x7 : ffff800080c70844 x6 : ffff800080c6cc44 x5 : ffff0000c8436d48 x4 : ffff8000a2257628 x3 : ffff8000851bda68 x2 : 0000000000000000 x1 : 0000000000000008 x0 : 0000000000000000 Call trace: mtd_get_master include/linux/mtd/mtd.h:405 [inline] (P) mtd_erase+0x94/0x56c drivers/mtd/mtdcore.c:1383 (P) jffs2_erase_block fs/jffs2/erase.c:63 [inline] jffs2_erase_pending_blocks+0x97c/0x1cd4 fs/jffs2/erase.c:140 jffs2_garbage_collect_pass+0x524/0x19c0 fs/jffs2/gc.c:253 jffs2_garbage_collect_thread+0x3c0/0x430 fs/jffs2/background.c:155 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 Code: 96d5cf8a aa1503f3 91192274 d343fe88 (387a6908) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 96d5cf8a bl 0xfffffffffb573e28 4: aa1503f3 mov x19, x21 8: 91192274 add x20, x19, #0x648 c: d343fe88 lsr x8, x20, #3 * 10: 387a6908 ldrb w8, [x8, x26] <-- trapping instruction