From 1786e0c96af1d455a4cc1632b7c36b838ca1232e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Date: Tue, 23 Apr 2024 12:34:25 +0200 Subject: [PATCH] admin-guide/hw-vuln/core-scheduling: fix return type of PR_SCHED_CORE_GET MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 8af2d1ab78f2342f8c4c3740ca02d86f0ebfac5a upstream. sched_core_share_pid() copies the cookie to userspace with put_user(id, (u64 __user *)uaddr), expecting 64 bits of space. The "unsigned long" datatype that is documented in core-scheduling.rst however is only 32 bits large on 32 bit architectures. Document "unsigned long long" as the correct data type that is always 64bits large. This matches what the selftest cs_prctl_test.c has been doing all along. Fixes: 0159bb020ca9 ("Documentation: Add usecases, design and interface for core scheduling") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/util-linux/df7a25a0-7923-4f8b-a527-5e6f0064074d@t-8ch.de/ Signed-off-by: Thomas Weißschuh Reviewed-by: Chris Hyser Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20240423-core-scheduling-cookie-v1-1-5753a35f8dfc@weissschuh.net Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/hw-vuln/core-scheduling.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/hw-vuln/core-scheduling.rst b/Documentation/admin-guide/hw-vuln/core-scheduling.rst index 0febe458597c..b9ab02325e8b 100644 --- a/Documentation/admin-guide/hw-vuln/core-scheduling.rst +++ b/Documentation/admin-guide/hw-vuln/core-scheduling.rst @@ -66,8 +66,8 @@ arg4: will be performed for all tasks in the task group of ``pid``. arg5: - userspace pointer to an unsigned long for storing the cookie returned by - ``PR_SCHED_CORE_GET`` command. Should be 0 for all other commands. + userspace pointer to an unsigned long long for storing the cookie returned + by ``PR_SCHED_CORE_GET`` command. Should be 0 for all other commands. In order for a process to push a cookie to, or pull a cookie from a process, it is required to have the ptrace access mode: `PTRACE_MODE_READ_REALCREDS` to the