6.9-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Weißschuh linux@weissschuh.net
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-8c... Signed-off-by: Thomas Weißschuh linux@weissschuh.net Reviewed-by: Chris Hyser chris.hyser@oracle.com Signed-off-by: Jonathan Corbet corbet@lwn.net Link: https://lore.kernel.org/r/20240423-core-scheduling-cookie-v1-1-5753a35f8dfc@... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/hw-vuln/core-scheduling.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/Documentation/admin-guide/hw-vuln/core-scheduling.rst +++ b/Documentation/admin-guide/hw-vuln/core-scheduling.rst @@ -67,8 +67,8 @@ 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