Re: [syzbot] KASAN: null-ptr-deref Read in __free_pages

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: null-ptr-deref Read in __free_pages

RBP: 00007ffd90d14ab0 R08: 0000000000000001 R09: 00007ffd90d10035
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffd90d14b10 R14: 000000000000000d R15: 00007f2697250490
 </TASK>
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [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:717 [inline]
BUG: KASAN: null-ptr-deref in __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
Read of size 4 at addr 0000000000000034 by task syz-executor333/4057

CPU: 0 PID: 4057 Comm: syz-executor333 Not tainted 5.17.0-syzkaller-00083-gf443e374ae13-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 __kasan_report mm/kasan/report.c:446 [inline]
 kasan_report.cold+0x66/0xdf mm/kasan/report.c:459
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:71 [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:717 [inline]
 __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
 watch_queue_set_size+0x4b1/0x640 kernel/watch_queue.c:276
 pipe_ioctl+0xac/0x2b0 fs/pipe.c:632
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f26971ddd49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 18 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd90d14aa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000031 RCX: 00007f26971ddd49
RDX: 0000000000000029 RSI: 0000000000005760 RDI: 0000000000000003
RBP: 00007ffd90d14ab0 R08: 0000000000000001 R09: 00007ffd90d10035
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffd90d14b10 R14: 000000000000000d R15: 00007f2697250490
 </TASK>
==================================================================


Tested on:

commit:         f443e374 Linux 5.17
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124166eb700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=19ca6f72fd444749
dashboard link: https://syzkaller.appspot.com/bug?extid=d55757faa9b80590767b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=109444dd700000