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Date:   Sun, 20 Mar 2022 15:04:18 -0700
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Subject: [syzbot] KASAN: null-ptr-deref Read in __free_pages
From:   syzbot <syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com>
To:     christophe.jaillet@wanadoo.fr, dhowells@redhat.com,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    56e337f2cf13 Revert "gpio: Revert regression in sysfs-gpio..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17e0a8c5700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d35f9bc6884af6c9
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
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=134e4e91700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=127bd083700000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=138601c5700000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=104601c5700000
console output: https://syzkaller.appspot.com/x/log.txt?x=178601c5700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc794ecea0 R14: 000000000000000d R15: 00007ff328525490
 </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-executor168/3599

CPU: 1 PID: 3599 Comm: syz-executor168 Not tainted 5.17.0-rc8-syzkaller-00003-g56e337f2cf13 #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+0x499/0x630 kernel/watch_queue.c:275
 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: 0033:0x7ff3284b2d59
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:00007ffc794ece38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000031 RCX: 00007ff3284b2d59
RDX: 0000000000000029 RSI: 0000000000005760 RDI: 0000000000000003
RBP: 00007ffc794ece40 R08: 0000000000000001 R09: 00007ffc794e0035
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc794ecea0 R14: 000000000000000d R15: 00007ff328525490
 </TASK>
==================================================================


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches