================================================================== BUG: KASAN: slab-use-after-free in gsm_cleanup_mux+0x720/0x7f4 drivers/tty/n_gsm.c:3052 Read of size 4 at addr ffff0000d188600c by task syz-executor.0/6443 CPU: 1 PID: 6443 Comm: syz-executor.0 Not tainted 6.5.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0x174/0x514 mm/kasan/report.c:475 kasan_report+0xd8/0x138 mm/kasan/report.c:588 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380 gsm_cleanup_mux+0x720/0x7f4 drivers/tty/n_gsm.c:3052 gsm_config drivers/tty/n_gsm.c:3327 [inline] gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2795 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Allocated by task 6436: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x7c mm/kasan/common.c:52 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:511 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:196 [inline] kmalloc_trace+0x70/0x88 mm/slab_common.c:1081 kmalloc include/linux/slab.h:582 [inline] kzalloc include/linux/slab.h:703 [inline] gsm_dlci_alloc+0x64/0x53c drivers/tty/n_gsm.c:2618 gsm_activate_mux+0x30/0x268 drivers/tty/n_gsm.c:3100 gsm_config drivers/tty/n_gsm.c:3355 [inline] gsmld_ioctl+0x162c/0x221c drivers/tty/n_gsm.c:3733 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2795 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Freed by task 6436: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x7c mm/kasan/common.c:52 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:522 ____kasan_slab_free+0x144/0x1c0 mm/kasan/common.c:236 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:162 [inline] slab_free_hook mm/slub.c:1792 [inline] slab_free_freelist_hook mm/slub.c:1818 [inline] slab_free mm/slub.c:3801 [inline] __kmem_cache_free+0x2ac/0x480 mm/slub.c:3814 kfree+0xb8/0x19c mm/slab_common.c:1034 gsm_dlci_free+0x11c/0x168 drivers/tty/n_gsm.c:2671 tty_port_destructor drivers/tty/tty_port.c:296 [inline] kref_put include/linux/kref.h:65 [inline] tty_port_put+0xfc/0x190 drivers/tty/tty_port.c:311 dlci_put drivers/tty/n_gsm.c:2681 [inline] gsm_dlci_release drivers/tty/n_gsm.c:2714 [inline] gsm_cleanup_mux+0x4ac/0x7f4 drivers/tty/n_gsm.c:3074 gsm_config drivers/tty/n_gsm.c:3327 [inline] gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2795 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 The buggy address belongs to the object at ffff0000d1886000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 12 bytes inside of freed 2048-byte region [ffff0000d1886000, ffff0000d1886800) The buggy address belongs to the physical page: page:000000001ebf12d6 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111880 head:000000001ebf12d6 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 05ffc00000010200 ffff0000c0002000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d1885f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000d1885f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000d1886000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d1886080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d1886100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== list_add corruption. prev is NULL. ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:24! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 6443 Comm: syz-executor.0 Tainted: G B 6.5.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023 pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __list_add_valid+0xcc/0x110 lib/list_debug.c:23 lr : __list_add_valid+0xcc/0x110 lib/list_debug.c:23 sp : ffff8000971d77e0 x29: ffff8000971d77e0 x28: ffff0000d418d094 x27: ffff0000c9465918 x26: ffff0000c9465910 x25: dfff800000000000 x24: 0000000000000000 x23: 0000000000000000 x22: ffff0000c94658c8 x21: ffff0000d418d080 x20: 1fffe0001928cb23 x19: ffff0000c9465500 x18: 1fffe0003683f9c6 x17: 0000000000000000 x16: ffff80008a55b464 x15: 0000000000000001 x14: 1fffe0003683fa2a x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000001 x10: 0000000000000000 x9 : 26da877a02f20a00 x8 : 26da877a02f20a00 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff8000971d70f8 x4 : ffff80008e15ef00 x3 : ffff8000805a1ab0 x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000022 Call trace: __list_add_valid+0xcc/0x110 lib/list_debug.c:23 __list_add include/linux/list.h:69 [inline] list_add_tail include/linux/list.h:102 [inline] gsm_send+0x350/0x604 drivers/tty/n_gsm.c:835 gsm_command drivers/tty/n_gsm.c:898 [inline] gsm_dlci_begin_close drivers/tty/n_gsm.c:2364 [inline] gsm_cleanup_mux+0x1a0/0x7f4 drivers/tty/n_gsm.c:3053 gsm_config drivers/tty/n_gsm.c:3327 [inline] gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2795 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Code: d4210000 b0040380 913c8000 95e84bb7 (d4210000) ---[ end trace 0000000000000000 ]---