Hello, syzbot found the following issue on: HEAD commit: 33afd4b76393 Merge tag 'mm-nonmm-stable-2023-04-27-16-01' .. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17bc1008280000 kernel config: https://syzkaller.appspot.com/x/.config?x=70288413d8a92398 dashboard link: https://syzkaller.appspot.com/bug?extid=48011b86c8ea329af1b9 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+48011b86c8ea329af1b9@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] BUG: KASAN: null-ptr-deref in page_ref_count include/linux/page_ref.h:67 [inline] BUG: KASAN: null-ptr-deref in put_page_testzero include/linux/mm.h:1007 [inline] BUG: KASAN: null-ptr-deref in folio_put_testzero include/linux/mm.h:1013 [inline] BUG: KASAN: null-ptr-deref in folio_put include/linux/mm.h:1440 [inline] BUG: KASAN: null-ptr-deref in filemap_fault+0x544/0x24a0 mm/filemap.c:3382 Read of size 4 at addr 0000000000000028 by task syz-executor.2/19418 CPU: 1 PID: 19418 Comm: syz-executor.2 Not tainted 6.3.0-syzkaller-10620-g33afd4b76393 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_report mm/kasan/report.c:465 [inline] kasan_report+0xec/0x130 mm/kasan/report.c:572 check_region_inline mm/kasan/generic.c:181 [inline] kasan_check_range+0x141/0x190 mm/kasan/generic.c:187 instrument_atomic_read include/linux/instrumented.h:68 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] page_ref_count include/linux/page_ref.h:67 [inline] put_page_testzero include/linux/mm.h:1007 [inline] folio_put_testzero include/linux/mm.h:1013 [inline] folio_put include/linux/mm.h:1440 [inline] filemap_fault+0x544/0x24a0 mm/filemap.c:3382 __do_fault+0x107/0x600 mm/memory.c:4176 do_read_fault mm/memory.c:4530 [inline] do_fault mm/memory.c:4659 [inline] do_pte_missing mm/memory.c:3647 [inline] handle_pte_fault mm/memory.c:4947 [inline] __handle_mm_fault+0x27f6/0x4170 mm/memory.c:5089 handle_mm_fault+0x2af/0x9f0 mm/memory.c:5243 do_user_addr_fault+0x51a/0x1210 arch/x86/mm/fault.c:1440 handle_page_fault arch/x86/mm/fault.c:1534 [inline] exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 RIP: 0023:0xf72255d0 Code: Unable to access opcode bytes at 0xf72255a6. RSP: 002b:00000000ffb4674c EFLAGS: 00010202 RAX: 00000000f734e000 RBX: 00000000f734e000 RCX: 00000000f737c038 RDX: 000000002e220000 RSI: 0000000000000004 RDI: 00000000000e257f RBP: 00000000f737c0c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the bug is already fixed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to change bug's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the bug is a duplicate of another bug, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
