[syzbot] memory leak in watch_queue_set_size

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 34e047aa16c0 Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16ac6f83700000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c80259f3b3fdf91
dashboard link: https://syzkaller.appspot.com/bug?extid=25ea042ae28f3888727a
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=15dc9c95700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15dd7871700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+25ea04...@syzkaller.appspotmail.com

Warning: Permanently added '10.128.10.51' (ECDSA) to the list of known hosts.
executing program
executing program
executing program
BUG: memory leak
unreferenced object 0xffff88810d9bc140 (size 32):
comm "syz-executor335", pid 3603, jiffies 4294946994 (age 12.840s)
hex dump (first 32 bytes):
40 a7 40 04 00 ea ff ff 00 00 00 00 00 00 00 00 @.@.............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81459bff>] kmalloc_array include/linux/slab.h:621 [inline]
[<ffffffff81459bff>] kcalloc include/linux/slab.h:652 [inline]
[<ffffffff81459bff>] watch_queue_set_size+0x12f/0x2e0 kernel/watch_queue.c:251
[<ffffffff8159fcf2>] pipe_ioctl+0x82/0x140 fs/pipe.c:632
[<ffffffff815b601c>] vfs_ioctl fs/ioctl.c:51 [inline]
[<ffffffff815b601c>] __do_sys_ioctl fs/ioctl.c:874 [inline]
[<ffffffff815b601c>] __se_sys_ioctl fs/ioctl.c:860 [inline]
[<ffffffff815b601c>] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860
[<ffffffff84493a05>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff84493a05>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

BUG: memory leak
unreferenced object 0xffff88810d9b2440 (size 32):
comm "syz-executor335", pid 3606, jiffies 4294947528 (age 7.500s)
hex dump (first 32 bytes):
40 4d 36 04 00 ea ff ff 00 00 00 00 00 00 00 00 @M6.............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81459bff>] kmalloc_array include/linux/slab.h:621 [inline]
[<ffffffff81459bff>] kcalloc include/linux/slab.h:652 [inline]
[<ffffffff81459bff>] watch_queue_set_size+0x12f/0x2e0 kernel/watch_queue.c:251
[<ffffffff8159fcf2>] pipe_ioctl+0x82/0x140 fs/pipe.c:632
[<ffffffff815b601c>] vfs_ioctl fs/ioctl.c:51 [inline]
[<ffffffff815b601c>] __do_sys_ioctl fs/ioctl.c:874 [inline]
[<ffffffff815b601c>] __se_sys_ioctl fs/ioctl.c:860 [inline]
[<ffffffff815b601c>] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860
[<ffffffff84493a05>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff84493a05>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae



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[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+25ea04...@syzkaller.appspotmail.com

Tested on:

commit: f0228146 Merge tag 'trace-v5.18-1' of git://git.kernel..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=5345e3f0a624ea04

dashboard link: https://syzkaller.appspot.com/bug?extid=25ea042ae28f3888727a
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=11706551700000

Note: testing is done by a robot and is best-effort only.