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Fri, 26 Dec 2025 23:38:27 -0800 (PST) Received: from localhost.localdomain ([176.33.65.121]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59a185dd90esm7345408e87.31.2025.12.26.23.38.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Dec 2025 23:38:26 -0800 (PST) From: Alper Ak To: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org Cc: Alper Ak , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Breno Leitao , Willem de Bruijn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] net: ipv4: ipmr: Prevent information leak in ipmr_sk_ioctl() Date: Sat, 27 Dec 2025 10:37:42 +0300 Message-ID: <20251227073743.17272-1-alperyasinak1@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" struct sioc_vif_req has a padding hole after the vifi field due to alignment requirements. These padding bytes were uninitialized, potentially leaking kernel stack memory to userspace when the struct is copied via sock_ioctl_inout(). Reported by Smatch: net/ipv4/ipmr.c:1575 ipmr_sk_ioctl() warn: check that 'buffer' doesn't leak information (struct has a hole after 'vifi') Fixes: e1d001fa5b47 ("net: ioctl: Use kernel memory on protocol ioctl callb= acks") Signed-off-by: Alper Ak --- net/ipv4/ipmr.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index ca9eaee4c2ef..18441fbe7ed7 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1571,6 +1571,7 @@ int ipmr_sk_ioctl(struct sock *sk, unsigned int cmd, = void __user *arg) /* These userspace buffers will be consumed by ipmr_ioctl() */ case SIOCGETVIFCNT: { struct sioc_vif_req buffer; + memset(&buffer, 0, sizeof(buffer)); =20 return sock_ioctl_inout(sk, cmd, arg, &buffer, sizeof(buffer)); --=20 2.43.0