netdev - Re: [syzbot] [cgroups?] general protection fault in __cgroup_rstat

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Message-ID: <qzzfped7jds7kcr466zahbrcw2eg5n6ke7drzxm6btexv36ca2@mici3xiuajuz>
Date: Tue, 17 Jun 2025 12:00:51 +0200
From: Michal Koutný <mkoutny@...e.com>
To: syzbot <syzbot+31eb4d4e7d9bc1fc1312@...kaller.appspotmail.com>, 
	inwardvessel@...il.com
Cc: akpm@...ux-foundation.org, andrii@...nel.org, ast@...nel.org, 
	axboe@...nel.dk, bpf@...r.kernel.org, cgroups@...r.kernel.org, 
	daniel@...earbox.net, eddyz87@...il.com, hannes@...xchg.org, haoluo@...gle.com, 
	hawk@...nel.org, john.fastabend@...il.com, jolsa@...nel.org, josef@...icpanda.com, 
	kpsingh@...nel.org, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-mm@...ck.org, martin.lau@...ux.dev, mhocko@...nel.org, 
	muchun.song@...ux.dev, mykolal@...com, netdev@...r.kernel.org, roman.gushchin@...ux.dev, 
	sdf@...ichev.me, shakeel.butt@...ux.dev, shuah@...nel.org, song@...nel.org, 
	syzkaller-bugs@...glegroups.com, tj@...nel.org, yonghong.song@...ux.dev
Subject: Re: [syzbot] [cgroups?] general protection fault in
 __cgroup_rstat_lock

On Mon, Jun 02, 2025 at 04:15:56PM +0200, Michal Koutný <mkoutny@...e.com> wrote:
> I'd say this might be relevant (although I don't see the possibly
> incorrect error handlnig path) but it doesn't mean this commit fixes it,
> it'd rather require the reproducer to adjust the N on this path.

Hm, possibly syzbot caught up here [1]:

-mkdir(&(0x7f0000000000)='./cgroup/file0\x00', 0xd0939199c36b4d28) (fail_nth: 8)
+mkdirat$cgroup_root(0xffffffffffffff9c, &(0x7f00000005c0)='./cgroup.net/syz0\x00', 0x1ff) (fail_nth: 23)

So there's something fishy in the error handling.

HTH,
Michal

[1] https://lore.kernel.org/lkml/68403875.a00a0220.d4325.000a.GAE@google.com/

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