================================================================== BUG: KASAN: slab-out-of-bounds in afs_split_string fs/afs/addr_prefs.c:51 [inline] BUG: KASAN: slab-out-of-bounds in afs_proc_addr_prefs_write+0x13a9/0x15f0 fs/afs/addr_prefs.c:415 Read of size 1 at addr ffff888140ed7fe7 by task syz.3.191/6673 CPU: 1 UID: 0 PID: 6673 Comm: syz.3.191 Tainted: G U 6.16.0-rc2-syzkaller #0 PREEMPT(full) Tainted: [U]=USER Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xcd/0x680 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 afs_split_string fs/afs/addr_prefs.c:51 [inline] afs_proc_addr_prefs_write+0x13a9/0x15f0 fs/afs/addr_prefs.c:415 proc_simple_write+0x117/0x1b0 fs/proc/generic.c:825 pde_write fs/proc/inode.c:330 [inline] proc_reg_write+0x240/0x330 fs/proc/inode.c:342 do_loop_readv_writev fs/read_write.c:850 [inline] do_loop_readv_writev fs/read_write.c:835 [inline] vfs_writev+0x5df/0xde0 fs/read_write.c:1059 do_writev+0x132/0x340 fs/read_write.c:1103 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f619638e929 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:00007f6197169038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f61965b5fa0 RCX: 00007f619638e929 RDX: 0000000000000003 RSI: 0000200000000080 RDI: 0000000000000009 RBP: 00007f6196410b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f61965b5fa0 R15: 00007ffd9164e4b8 Allocated by task 6673: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4328 [inline] __kmalloc_node_track_caller_noprof+0x221/0x510 mm/slub.c:4347 memdup_user_nul+0x2b/0x120 mm/util.c:302 proc_simple_write+0xc7/0x1b0 fs/proc/generic.c:822 pde_write fs/proc/inode.c:330 [inline] proc_reg_write+0x240/0x330 fs/proc/inode.c:342 do_loop_readv_writev fs/read_write.c:850 [inline] do_loop_readv_writev fs/read_write.c:835 [inline] vfs_writev+0x5df/0xde0 fs/read_write.c:1059 do_writev+0x132/0x340 fs/read_write.c:1103 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888140ed7fe0 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes to the right of allocated 7-byte region [ffff888140ed7fe0, ffff888140ed7fe7) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x140ed7 flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 057ff00000000000 ffff88801b841500 dead000000000100 dead000000000122 raw: 0000000000000000 0000000080800080 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 2525201406, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419 alloc_slab_page mm/slub.c:2451 [inline] allocate_slab mm/slub.c:2619 [inline] new_slab+0x23b/0x330 mm/slub.c:2673 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949 __slab_alloc_node mm/slub.c:4024 [inline] slab_alloc_node mm/slub.c:4185 [inline] __do_kmalloc_node mm/slub.c:4327 [inline] __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340 kmalloc_noprof include/linux/slab.h:909 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] lsm_blob_alloc+0x68/0x90 security/security.c:684 lsm_superblock_alloc security/security.c:862 [inline] security_sb_alloc+0x28/0x230 security/security.c:1409 alloc_super+0x23d/0xbd0 fs/super.c:347 sget_fc+0x116/0xc20 fs/super.c:761 vfs_get_super fs/super.c:1318 [inline] get_tree_single+0x2d/0x190 fs/super.c:1350 debugfs_get_tree+0x38/0x50 fs/debugfs/inode.c:288 vfs_get_tree+0x8e/0x340 fs/super.c:1802 fc_mount fs/namespace.c:1290 [inline] vfs_kern_mount.part.0+0xcf/0x1c0 fs/namespace.c:1320 page_owner free stack trace missing Memory state around the buggy address: ffff888140ed7e80: 05 fc fc fc 04 fc fc fc fa fc fc fc fa fc fc fc ffff888140ed7f00: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc >ffff888140ed7f80: fa fc fc fc fa fc fc fc fa fc fc fc 07 fc fc fc ^ ffff888140ed8000: 00 fc fc fc 07 fc fc fc 04 fc fc fc 07 fc fc fc ffff888140ed8080: 00 fc fc fc 06 fc fc fc 00 fc fc fc 07 fc fc fc ==================================================================