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AJvYcCVOA+6AKcCX9kUvZ1Y07W1ht5GAxP5GYcPGtaAC3bdl8HvnbZG0axCvYxikdm1KOjvhUrnhXCdO@vger.kernel.org, AJvYcCVTYKUmsbeSBkaL4Ho1SQAXb3gzosI+EkzgSxLys4VUL1+3FIIGHEdcqlsiemsMtJ3bSE4QQAWymjwh2Rc=@vger.kernel.org, AJvYcCWlv/u/PUkfPbFglUk4fLkh0JnR0S0INCaQ3L+/VYbw1PsbevEb38p6M1BL5eBRJ874zAJfLZebH9SNWQ==@vger.kernel.org X-Gm-Message-State: AOJu0YxNDdW/WFXIjxKH5wbru14H6lX+9SmVlZ5nTzQXrKR6u7NfF2iY AOZ38gTprh+Rco76U1LiKbNM6bbzc4/D869TmwKJULcJ2xrgCBTgbe6NsHUmGbk= X-Google-Smtp-Source: AGHT+IFBqDxOxf1PfVYJckn+qxMYKlRIW2aAqR5G/gwisPE+GQFN8erp7XgljKTDwF3QpbDf1rsfWw== X-Received: by 2002:a05:6a00:1909:b0:71e:818a:97d9 with SMTP id d2e1a72fcca58-72413278818mr16586268b3a.5.1731330286874; Mon, 11 Nov 2024 05:04:46 -0800 (PST) Received: from kernelexploit-virtual-machine.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724078a7c50sm9355801b3a.60.2024.11.11.05.04.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Nov 2024 05:04:46 -0800 (PST) From: Jeongjun Park To: devnull+manas18244.iiitd.ac.in@kernel.org Cc: alibuda@linux.alibaba.com, anupnewsmail@gmail.com, davem@davemloft.net, edumazet@google.com, guwen@linux.alibaba.com, horms@kernel.org, jaka@linux.ibm.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, manas18244@iiitd.ac.in, netdev@vger.kernel.org, pabeni@redhat.com, shuah@kernel.org, tonylu@linux.alibaba.com, wenjia@linux.ibm.com Subject: Re: [PATCH] Remove unused function parameter in __smc_diag_dump Date: Mon, 11 Nov 2024 22:04:39 +0900 Message-Id: <20241111130439.7536-1-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241109-fix-oops-__smc_diag_dump-v1-1-1c55a3e54ad4@iiitd.ac.in> References: <20241109-fix-oops-__smc_diag_dump-v1-1-1c55a3e54ad4@iiitd.ac.in> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Manas wrote: > The last parameter in __smc_diag_dump (struct nlattr *bc) is unused. > There is only one instance of this function being called and its passed > with a NULL value in place of bc. > > Signed-off-by: Manas > --- > The last parameter in __smc_diag_dump (struct nlattr *bc) is unused. > There is only one instance of this function being called and its passed > with a NULL value in place of bc. > > Though, the compiler (gcc) optimizes it. Looking at the object dump of > vmlinux (via `objdump -D vmlinux`), a new function clone > (__smc_diag_dump.constprop.0) is added which removes this parameter from > calling convention altogether. > > ffffffff8a701770 <__smc_diag_dump.constprop.0>: > ffffffff8a701770: 41 57 push %r15 > ffffffff8a701772: 41 56 push %r14 > ffffffff8a701774: 41 55 push %r13 > ffffffff8a701776: 41 54 push %r12 > > There are 5 parameters in original function, but in the cloned function > only 4. > > I believe this patch also fixes this oops bug[1], which arises in the > same function __smc_diag_dump. But I couldn't verify it further. Can > someone please test this? > > [1] https://syzkaller.appspot.com/bug?extid=271fed3ed6f24600c364 Unfortunately, I tested it myself and this bug is still triggering. Basically, this bug is not triggered in normal situations, but triggered when a race condition occurs, so I think the root cause is somewhere else. Regards, Jeongjun Park > --- > net/smc/smc_diag.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c > index 6fdb2d96777ad704c394709ec845f9ddef5e599a..8f7bd40f475945171a0afa5a2cce12d9aa2b1eb4 100644 > --- a/net/smc/smc_diag.c > +++ b/net/smc/smc_diag.c > @@ -71,8 +71,7 @@ static int smc_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb, > > static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb, > struct netlink_callback *cb, > - const struct smc_diag_req *req, > - struct nlattr *bc) > + const struct smc_diag_req *req) > { > struct smc_sock *smc = smc_sk(sk); > struct smc_diag_fallback fallback; > @@ -199,7 +198,6 @@ static int smc_diag_dump_proto(struct proto *prot, struct sk_buff *skb, > struct smc_diag_dump_ctx *cb_ctx = smc_dump_context(cb); > struct net *net = sock_net(skb->sk); > int snum = cb_ctx->pos[p_type]; > - struct nlattr *bc = NULL; > struct hlist_head *head; > int rc = 0, num = 0; > struct sock *sk; > @@ -214,7 +212,7 @@ static int smc_diag_dump_proto(struct proto *prot, struct sk_buff *skb, > continue; > if (num < snum) > goto next; > - rc = __smc_diag_dump(sk, skb, cb, nlmsg_data(cb->nlh), bc); > + rc = __smc_diag_dump(sk, skb, cb, nlmsg_data(cb->nlh)); > if (rc < 0) > goto out; > next: > > --- > base-commit: 59b723cd2adbac2a34fc8e12c74ae26ae45bf230 > change-id: 20241109-fix-oops-__smc_diag_dump-06ab3e9d39f4 > > Best regards, > -- > Manas