================================================================== BUG: KASAN: use-after-free in strlen+0x79/0x90 lib/string.c:544 Read of size 1 at addr ffff8881a5e23a08 by task syz-executor.1/13893 CPU: 0 PID: 13893 Comm: syz-executor.1 Not tainted 5.6.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xef/0x16e lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374 __kasan_report.cold+0x37/0x77 mm/kasan/report.c:506 kasan_report+0xe/0x20 mm/kasan/common.c:641 strlen+0x79/0x90 lib/string.c:544 strlen include/linux/string.h:303 [inline] str_to_user+0x27/0x90 drivers/input/evdev.c:780 evdev_do_ioctl drivers/input/evdev.c:1183 [inline] evdev_ioctl_handler+0x130a/0x19f0 drivers/input/evdev.c:1281 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c849 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f6a282d0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6a282d16d4 RCX: 000000000045c849 RDX: 0000000020000100 RSI: 0000000080404507 RDI: 0000000000000004 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002ca R14: 00000000004c51be R15: 000000000076bf0c Allocated by task 245: save_stack+0x1b/0x80 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488 kmalloc include/linux/slab.h:555 [inline] syslog_print kernel/printk/printk.c:1356 [inline] do_syslog kernel/printk/printk.c:1529 [inline] do_syslog+0x53b/0x1380 kernel/printk/printk.c:1503 kmsg_read+0x8a/0xb0 fs/proc/kmsg.c:40 proc_reg_read+0x1c1/0x280 fs/proc/inode.c:223 __vfs_read+0x76/0x100 fs/read_write.c:425 vfs_read+0x1ea/0x430 fs/read_write.c:461 ksys_read+0x127/0x250 fs/read_write.c:587 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 245: save_stack+0x1b/0x80 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x117/0x160 mm/kasan/common.c:476 slab_free_hook mm/slub.c:1444 [inline] slab_free_freelist_hook mm/slub.c:1477 [inline] slab_free mm/slub.c:3034 [inline] kfree+0xd5/0x300 mm/slub.c:3995 syslog_print kernel/printk/printk.c:1415 [inline] do_syslog kernel/printk/printk.c:1529 [inline] do_syslog+0x1104/0x1380 kernel/printk/printk.c:1503 kmsg_read+0x8a/0xb0 fs/proc/kmsg.c:40 proc_reg_read+0x1c1/0x280 fs/proc/inode.c:223 __vfs_read+0x76/0x100 fs/read_write.c:425 vfs_read+0x1ea/0x430 fs/read_write.c:461 ksys_read+0x127/0x250 fs/read_write.c:587 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881a5e23800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 520 bytes inside of 1024-byte region [ffff8881a5e23800, ffff8881a5e23c00) The buggy address belongs to the page: page:ffffea0006978800 refcount:1 mapcount:0 mapping:ffff8881da002280 index:0x0 compound_mapcount: 0 flags: 0x200000000010200(slab|head) raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da002280 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881a5e23900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881a5e23980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881a5e23a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881a5e23a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881a5e23b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================