Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Song Liu <songliubraving@fb.com>
To:     "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
CC:     Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, Yonghong Song <yhs@fb.com>,
        bpf <bpf@vger.kernel.org>, Kernel Team <Kernel-team@fb.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] tracing/kprobes: Check whether get_kretprobe() returns
 NULL in kretprobe_dispatcher()
Thread-Topic: [PATCH] tracing/kprobes: Check whether get_kretprobe() returns
 NULL in kretprobe_dispatcher()
Thread-Index: AQHYceI9+nNYqnip2EqaqGe+bD34G6025gMA
Date:   Mon, 30 May 2022 05:19:53 +0000
Message-ID: <5EBCF33B-D777-4763-ADC3-0EBE676AC220@fb.com>
References: <165366693881.797669.16926184644089588731.stgit@devnote2>
In-Reply-To: <165366693881.797669.16926184644089588731.stgit@devnote2>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?5uRNC9BU+a/PO6vgX6yjSMKTnurycMPfWWLTIOHBJSksd6oKqloDAXDQ/kGg?=
 =?us-ascii?Q?gRIbINFMyRDAl3iSXqABUkDwAbrmFHqwow1+jVTCFDTe+UfRHAam1ss+++70?=
 =?us-ascii?Q?b/HJzGkRWGHlNFUnGtqnEpx7bcxNbVlkck0Xwbjw2rnXoi9l5HkuEB2SD5fZ?=
 =?us-ascii?Q?P9v1+DiZEChjcgqPth36q5snaE8wl2MlaXeuHpN64tKfJJ11bTG6Ju4ta7iT?=
 =?us-ascii?Q?Mg7aS+cwZSHGpn0q5ggeTXrPJuMhFT9QTvHej31KW62YVewAaQgz+aKPggBu?=
 =?us-ascii?Q?Fb5RdShpCIP1kbZMHkmKnA/kP8soCQqQCh/QZW687TFbuNyGaJZuuCBfaTe+?=
 =?us-ascii?Q?r9bcUqJnBcmHJQ2+F7T9cP1KQWA348yngkGp9jXTDHVBwbquU20bECI8mJ5p?=
 =?us-ascii?Q?Ovcbi5IhHx/bmPqeXebRe26VVunFwOcoTWQwuvRHAoIIpYCMVn6mh4qa+pp6?=
 =?us-ascii?Q?EMAPubpUrmP1EWkT3fA3x2eu4i1gNTDrB5CzH5BwLWth6bUiwZz5ziM9Usa7?=
 =?us-ascii?Q?NisK4ZAezaRWATHqpHDJc2hHM6Gbsn5NDFVKn1uBDrJcb3pGoQ7LNG+4Iqcl?=
 =?us-ascii?Q?IbDElqsXa7A6y14UNLB6GCC2h9Qt9dHpCNIkAcF899tzEs5WUNiqi3katA8u?=
 =?us-ascii?Q?YSIojKaUGySR+8wbb/VC4aCaSJcCtt8p/z7BD1AZqdEZ4be+EWiFparql2AX?=
 =?us-ascii?Q?wqI/SyLncSN6/9qW+yLGZswBrtQO1EmOfH8lE3A/bQuipQCQwnY9JC0HFaZ8?=
 =?us-ascii?Q?mX5bWOcrcH+ExiVrQyJU8kOwLbKfA8m2JWtdu/Nktho1+O3EZ3VtlKrKP0id?=
 =?us-ascii?Q?aKtavi2niDrdGNwPiWbY32n3iP30kz0kRuHqxJDJ/dvgw+qxujfF5hvViqUV?=
 =?us-ascii?Q?uFL0DcCHV5/EMppeqBXMbcwWYR5wg/i09GTWYklT21q0eqWRHxyphsGrxevD?=
 =?us-ascii?Q?v2xCmidswp+hHfH+YX7D1zRVAfMBmXcBllR2FBJTz6wiWm4KaMgYBT8P0mMv?=
 =?us-ascii?Q?2TOfbGRdkzHaaNrYwOvRtW/cxyBI9tpR7J87swnmND6oJscnXHoN3mDCWadG?=
 =?us-ascii?Q?5SMURRYc2hMsEM2vguQj7IYq8KxdR4vX2HMkUPwBWnISr/tIfdPIbLw+Mgh4?=
 =?us-ascii?Q?uCPVKBGVIYtJtUnimjdvJJaylRPBFwzqB8sYPSB4Ag3FIEvECE0RBN/0UFu0?=
 =?us-ascii?Q?8COmPcUkNi/he5xlkextSWND5RTOWGSHL//7MIbWDtUMPLqhYwO53stfpzcE?=
 =?us-ascii?Q?CJFLBn/PmBJ9d2x4mIEzWXmAmoM8/c9QO6Leegqd/oTIEvip+kjEgfRVzWPl?=
 =?us-ascii?Q?qMrhBrbaOMZz8NktxYL+nXES6kZQM+yOHi80UtxRbdKA9o9yCCn93++6vhKM?=
 =?us-ascii?Q?LAs+zDkUxl7T4nrkxrCib/SNyOiBVDOWs47MnAX836dO1i9bICvUw6lFC+Uj?=
 =?us-ascii?Q?xzLtStp6UzE8V3e5WIBypcPOz7T4MgnK9Yh7cYdP/YpoT83chmrTDKKl+2Sm?=
 =?us-ascii?Q?a4UkHfg0moOoDIbW3tn/iuGdbtCCuJbGq+bKIjsNxVenUBvYEl+q2KDDBYBl?=
 =?us-ascii?Q?1DdvewUo04bM4nD9OxuPp6u5snhIbTtqtudcMNMlwjdY3Dwnrm6dgHrJQOX2?=
 =?us-ascii?Q?3YK6RVEeXioEBkQULzqYTkPilY4eIpnpfaJmK1moZDYUvCzuFEtOsZzpLdAY?=
 =?us-ascii?Q?/LZX2wReEWB5UULt4kc1aLKcmC1t9TBG+mB0xDi/Z8ISoNXtNSwVH4k4A4lu?=
 =?us-ascii?Q?4OXEKGGd2nNVZ89lXGg5ysF0nt0wLX1UTJ3FqPPv5lKPOxJURfJI?=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <1EB8AF69DD47C74381B20341D43D1EAE@namprd15.prod.outlook.com>
MIME-Version: 1.0
X-OriginatorOrg: fb.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: SA1PR15MB5109.namprd15.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7b7b48eb-e84e-488d-7bd2-08da41fc0752
X-MS-Exchange-CrossTenant-originalarrivaltime: 30 May 2022 05:19:53.6287
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: RlAzn4G7yq6bW6wR/UCNfk9xoBHpfEZUGAe2Q/vtwfH+C6C8LitFOka2ARHb0fmV4ORitGql3iLHxfmzbI4DjA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB4108
X-Proofpoint-GUID: cKFkQRDjqyuI5-ex_Zp3k7vJjWW8yAg0
X-Proofpoint-ORIG-GUID: cKFkQRDjqyuI5-ex_Zp3k7vJjWW8yAg0
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.486,FMLib:17.11.64.514
 definitions=2022-05-30_01,2022-05-27_01,2022-02-23_01
X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


> On May 27, 2022, at 8:55 AM, Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> There is a small chance that get_kretprobe(ri) returns NULL in
> kretprobe_dispatcher() when another CPU unregisters the kretprobe
> right after __kretprobe_trampoline_handler().
> 
> To avoid this issue, kretprobe_dispatcher() checks the get_kretprobe()
> return value again. And if it is NULL, it returns soon because that
> kretprobe is under unregistering process.
> 
> This issue has been introduced when the kretprobe is decoupled
> from the struct kretprobe_instance by commit d741bf41d7c7
> ("kprobes: Remove kretprobe hash"). Before that commit, the
> struct kretprob_instance::rp directly points the kretprobe
> and it is never be NULL.
> 
> Reported-by: Yonghong Song <yhs@fb.com>
> Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash")
> Cc: stable@vger.kernel.org
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Acked-by: Song Liu <song@kernel.org>

[...]