6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hui Peng commit 538b529509c7ab0d909cb65bb7264edca1788d30 upstream. 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. Cc: stable@vger.kernel.org Reviewed-by: Xin Long Signed-off-by: Hui Peng Fixes: f952be79cebd ("sctp: introduce struct sctp_stream_out_ext") Link: https://patch.msgid.link/20260930044611.204739-1-benquike@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sctp/socket.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -7516,11 +7516,7 @@ static int sctp_getsockopt_pr_streamstat /* 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++) {