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[34.82.187.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a4cae9ffaesm1339773a91.16.2026.09.29.21.46.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 21:46:13 -0700 (PDT) From: Hui Peng To: "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Xin Long , Vlad Yasevich , Neil Horman , linux-sctp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Hui Peng Subject: [PATCH net-next v2] sctp: copy zeroed stats to user in sctp_getsockopt_pr_streamstatus() when !streamoute Date: Wed, 30 Sep 2026 04:46:11 +0000 Message-ID: <20260930044611.204739-1-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When an SCTP stream output extension structure (streamoute) has not yet been allocated, sctp_getsockopt_pr_streamstatus() sets the local stack variables params.sprstat_abandoned_unsent = 0 and params.sprstat_abandoned_sent = 0, but then immediately jumps to 'out:', bypassing copy_to_user(). As a result, when an uninitialized user buffer is passed to getsockopt(SCTP_PR_STREAM_STATUS), the kernel returns success (0) without copying the zeroed stats back to user space, leaving uninitialized data in the user buffer. Refactor the !streamoute check into an if-else chain so that when streamoute is NULL, params is zeroed and falls through to copy_to_user(), copying the zeroed stats to user space and setting retval = 0 once before returning. Tested in QEMU against Linux 7.3.0-rc3 using an uninitialized sctp_prstatus user struct passed to getsockopt(SCTP_PR_STREAM_STATUS) on a freshly created stream: on the unfixed kernel the user struct contains uninitialized stack garbage; whereas with this fix applied, getsockopt() copies zeroed stats into user space and returns 0. Fixes: 28b7eab0f910 ("sctp: add SCTP_PR_STREAM_STATUS getsockopt") Cc: stable@vger.kernel.org Reviewed-by: Xin Long Assisted-by: LLM Signed-off-by: Hui Peng --- Changes in v2: - Re-target subject tag to [PATCH net-next v2]. - Remove redundant retval = 0 assignment in !streamoute block and fall through to copy_to_user() as suggested by Paolo Abeni and Xin Long. net/sctp/socket.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index c7b9e325ec1c..1aa475d9dfdb 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -7569,11 +7569,7 @@ static int sctp_getsockopt_pr_streamstatus(struct sock *sk, int len, /* Not allocated yet, means all stats are 0 */ params.sprstat_abandoned_unsent = 0; params.sprstat_abandoned_sent = 0; - retval = 0; - goto out; - } - - if (policy == SCTP_PR_SCTP_ALL) { + } else if (policy == SCTP_PR_SCTP_ALL) { params.sprstat_abandoned_unsent = 0; params.sprstat_abandoned_sent = 0; for (policy = 0; policy <= SCTP_PR_INDEX(MAX); policy++) {