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Thomas Orgis" , Yiyang Chen Subject: [PATCH 1/2] taskstats: return -EBADF when cgroupstats receives an invalid fd Date: Sat, 11 Jul 2026 04:07:36 +0800 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit cgroupstats_user_cmd() returns 0 without sending a reply or a netlink error when the fd passed via CGROUPSTATS_CMD_ATTR_FD does not resolve to an open file in the caller's table. As a result: - clients that did not set NLM_F_ACK block on recv() indefinitely waiting for a CGROUPSTATS_CMD_NEW message that is never emitted; - clients that set NLM_F_ACK receive a misleading "success" ACK (errno == 0) with no statistics payload. Return -EBADF instead so the netlink layer propagates the error to userspace as expected. Signed-off-by: Yiyang Chen --- kernel/taskstats.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/taskstats.c b/kernel/taskstats.c index 2cd0172d0516..8d115670a3ca 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -423,7 +423,7 @@ static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info) fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]); CLASS(fd, f)(fd); if (fd_empty(f)) - return 0; + return -EBADF; size = nla_total_size(sizeof(struct cgroupstats)); -- 2.43.0