================================================================== BUG: KASAN: use-after-free in gsm_cleanup_mux+0x700/0x7d8 drivers/tty/n_gsm.c:2491 Read of size 4 at addr ffff00012d04800c by task syz-executor.5/5133 CPU: 0 PID: 5133 Comm: syz-executor.5 Not tainted 6.1.25-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x174/0x4c0 mm/kasan/report.c:395 kasan_report+0xd4/0x130 mm/kasan/report.c:495 __asan_report_load4_noabort+0x2c/0x38 mm/kasan/report_generic.c:350 gsm_cleanup_mux+0x700/0x7d8 drivers/tty/n_gsm.c:2491 gsm_config drivers/tty/n_gsm.c:2754 [inline] gsmld_ioctl+0x9d4/0x1384 drivers/tty/n_gsm.c:3117 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2782 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+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 Allocated by task 5130: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace+0x7c/0x94 mm/slab_common.c:1050 kmalloc include/linux/slab.h:553 [inline] kzalloc include/linux/slab.h:689 [inline] gsm_dlci_alloc+0x60/0x340 drivers/tty/n_gsm.c:2064 gsm_activate_mux+0x30/0x268 drivers/tty/n_gsm.c:2538 gsm_config drivers/tty/n_gsm.c:2778 [inline] gsmld_ioctl+0xbc0/0x1384 drivers/tty/n_gsm.c:3117 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2782 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+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 Freed by task 5130: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516 ____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:177 [inline] slab_free_hook mm/slub.c:1724 [inline] slab_free_freelist_hook mm/slub.c:1750 [inline] slab_free mm/slub.c:3661 [inline] __kmem_cache_free+0x2c0/0x4b4 mm/slub.c:3674 kfree+0xcc/0x1b8 mm/slab_common.c:1007 gsm_dlci_free+0x11c/0x168 drivers/tty/n_gsm.c:2110 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:2120 [inline] gsm_dlci_release drivers/tty/n_gsm.c:2153 [inline] gsm_cleanup_mux+0x48c/0x7d8 drivers/tty/n_gsm.c:2512 gsm_config drivers/tty/n_gsm.c:2754 [inline] gsmld_ioctl+0x9d4/0x1384 drivers/tty/n_gsm.c:3117 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2782 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+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 The buggy address belongs to the object at ffff00012d048000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 12 bytes inside of 2048-byte region [ffff00012d048000, ffff00012d048800) The buggy address belongs to the physical page: page:00000000c173ecb2 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16d048 head:00000000c173ecb2 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc0004b38000 dead000000000002 ffff0000c0002900 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff00012d047f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff00012d047f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff00012d048000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff00012d048080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff00012d048100: 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 ee8d2e6ce5ef2e8e KASAN: maybe wild-memory-access in range [0x746d73672f797470-0x746d73672f797477] 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 CM = 0, WnR = 0 [ee8d2e6ce5ef2e8e] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 5133 Comm: syz-executor.5 Tainted: G B 6.1.25-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __list_add_valid+0x5c/0x110 lib/list_debug.c:30 lr : __list_add include/linux/list.h:69 [inline] lr : list_add_tail include/linux/list.h:102 [inline] lr : gsm_send+0x350/0x604 drivers/tty/n_gsm.c:726 sp : ffff80001f5078a0 x29: ffff80001f5078a0 x28: ffff0000c18cd114 x27: ffff00012ad10c18 x26: ffff00012ad10c10 x25: dfff800000000000 x24: 746d73672f797474 x23: dfff800000000000 x22: ffff00012ad10c18 x21: ffff0000c18cd100 x20: 746d73672f797474 x19: ffff00012ad10c10 x18: 1fffe000368b6b76 x17: ffff80000b5a9498 x16: ffff80000831b750 x15: ffff80000b5dbbf8 x14: ffff80000b5dc46c x13: ffff800008021d48 x12: ffff700003ea0f00 x11: 1ffff00003ea0f00 x10: 0000000000000004 x9 : 25a889068cc13c00 x8 : 0e8dae6ce5ef2e8e x7 : ffff800008967f44 x6 : ffff80000b5dc714 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff80000831b8ec x2 : 746d73672f797474 x1 : 746d73672f797474 x0 : ffff0000c18cd100 Call trace: __list_add_valid+0x5c/0x110 lib/list_debug.c:30 __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:726 gsm_command drivers/tty/n_gsm.c:789 [inline] gsm_dlci_begin_close drivers/tty/n_gsm.c:1933 [inline] gsm_cleanup_mux+0x1a0/0x7d8 drivers/tty/n_gsm.c:2492 gsm_config drivers/tty/n_gsm.c:2754 [inline] gsmld_ioctl+0x9d4/0x1384 drivers/tty/n_gsm.c:3117 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2782 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+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 Code: f94002c2 eb14005f 54000461 d343fe88 (38776908) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: f94002c2 ldr x2, [x22] 4: eb14005f cmp x2, x20 8: 54000461 b.ne 0x94 // b.any c: d343fe88 lsr x8, x20, #3 * 10: 38776908 ldrb w8, [x8, x23] <-- trapping instruction