================================================================== BUG: KASAN: slab-use-after-free in gsm_cleanup_mux+0x855/0x940 drivers/tty/n_gsm.c:3052 Read of size 4 at addr ffff88814132700c by task syz-executor167/5027 CPU: 1 PID: 5027 Comm: syz-executor167 Not tainted 6.3.0-syzkaller-13164-g78b421b6a7c6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:351 [inline] print_report+0x163/0x540 mm/kasan/report.c:462 kasan_report+0x176/0x1b0 mm/kasan/report.c:572 gsm_cleanup_mux+0x855/0x940 drivers/tty/n_gsm.c:3052 gsm_config drivers/tty/n_gsm.c:3327 [inline] gsmld_ioctl+0x1305/0x2460 drivers/tty/n_gsm.c:3733 tty_ioctl+0x989/0xda0 drivers/tty/tty_io.c:2786 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f679bc9ac79 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f679bc2b318 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f679bd224d8 RCX: 00007f679bc9ac79 RDX: 0000000020000040 RSI: 00000000404c4701 RDI: 0000000000000005 RBP: 00007f679bd224d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f679bcf007c R13: 00007ffc92a21c7f R14: 00007f679bc2b400 R15: 0000000000022000 Allocated by task 5026: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383 kmalloc include/linux/slab.h:559 [inline] kzalloc include/linux/slab.h:680 [inline] gsm_dlci_alloc+0x56/0x6e0 drivers/tty/n_gsm.c:2618 gsm_activate_mux+0x1c/0x290 drivers/tty/n_gsm.c:3100 gsm_config drivers/tty/n_gsm.c:3355 [inline] gsmld_ioctl+0x1746/0x2460 drivers/tty/n_gsm.c:3733 tty_ioctl+0x989/0xda0 drivers/tty/tty_io.c:2786 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 5026: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236 kasan_slab_free include/linux/kasan.h:162 [inline] slab_free_hook mm/slub.c:1781 [inline] slab_free_freelist_hook mm/slub.c:1807 [inline] slab_free mm/slub.c:3786 [inline] __kmem_cache_free+0x264/0x3c0 mm/slub.c:3799 dlci_put drivers/tty/n_gsm.c:2681 [inline] gsm_dlci_release drivers/tty/n_gsm.c:2714 [inline] gsm_cleanup_mux+0x5af/0x940 drivers/tty/n_gsm.c:3074 gsm_config drivers/tty/n_gsm.c:3327 [inline] gsmld_ioctl+0x1305/0x2460 drivers/tty/n_gsm.c:3733 tty_ioctl+0x989/0xda0 drivers/tty/tty_io.c:2786 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888141327000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 12 bytes inside of freed 2048-byte region [ffff888141327000, ffff888141327800) The buggy address belongs to the physical page: page:ffffea000504c800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x141320 head:ffffea000504c800 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 057ff00000010200 ffff888012442000 ffffea0005002800 dead000000000002 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 8581455090, free_ts 0 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1731 prep_new_page mm/page_alloc.c:1738 [inline] get_page_from_freelist+0x321c/0x33a0 mm/page_alloc.c:3502 __alloc_pages+0x255/0x670 mm/page_alloc.c:4768 alloc_page_interleave+0x22/0x1d0 mm/mempolicy.c:2112 alloc_slab_page+0x6a/0x160 mm/slub.c:1851 allocate_slab mm/slub.c:1998 [inline] new_slab+0x84/0x2f0 mm/slub.c:2051 ___slab_alloc+0xa85/0x10a0 mm/slub.c:3192 __slab_alloc mm/slub.c:3291 [inline] __slab_alloc_node mm/slub.c:3344 [inline] slab_alloc_node mm/slub.c:3441 [inline] __kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3490 kmalloc_node_trace+0x27/0xe0 mm/slab_common.c:1070 kmalloc_node include/linux/slab.h:575 [inline] kzalloc_node include/linux/slab.h:691 [inline] __alloc_disk_node+0x60/0x590 block/genhd.c:1385 __blk_mq_alloc_disk+0xf5/0x190 block/blk-mq.c:4092 nbd_dev_add+0x37e/0xaa0 drivers/block/nbd.c:1788 nbd_init+0x21d/0x2d0 drivers/block/nbd.c:2534 do_one_initcall+0x23d/0x7d0 init/main.c:1246 do_initcall_level+0x157/0x210 init/main.c:1319 do_initcalls+0x3f/0x80 init/main.c:1335 page_owner free stack trace missing Memory state around the buggy address: ffff888141326f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888141326f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888141327000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888141327080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888141327100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================