[PATCH v3] iouring:added boundary value check for io_uring_group systl

[PATCH v3] iouring:added boundary value check for io_uring_group systl

[Subramanya Swamy]

/proc/sys/kernel/io_uring_group takes gid as input
added boundary value check to accept gid in range of
0<=gid<=4294967294 & Documentation is updated for same

Fixes: 76d3ccecfa18 ("io_uring: add a sysctl to disable io_uring system-wide")

Signed-off-by: Subramanya Swamy <subramanya.swamy.linux@gmail.com>
---
 Documentation/admin-guide/sysctl/kernel.rst | 4 +---
 io_uring/io_uring.c                         | 8 ++++++--
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 6584a1f9bfe3..262d92f51fa5 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -471,9 +471,7 @@ io_uring_group
 
 When io_uring_disabled is set to 1, a process must either be
 privileged (CAP_SYS_ADMIN) or be in the io_uring_group group in order
-to create an io_uring instance.  If io_uring_group is set to -1 (the
-default), only processes with the CAP_SYS_ADMIN capability may create
-io_uring instances.
+to create an io_uring instance.
 
 
 kexec_load_disabled
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index cd9a137ad6ce..bd6cc0391efa 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -154,9 +154,11 @@ static void io_queue_sqe(struct io_kiocb *req);
 struct kmem_cache *req_cachep;
 
 static int __read_mostly sysctl_io_uring_disabled;
-static int __read_mostly sysctl_io_uring_group = -1;
+static unsigned int __read_mostly sysctl_io_uring_group;
 
 #ifdef CONFIG_SYSCTL
+static unsigned int max_gid  = ((gid_t) ~0U) - 1; /*4294967294 is the max guid*/
+
 static struct ctl_table kernel_io_uring_disabled_table[] = {
 	{
 		.procname	= "io_uring_disabled",
@@ -172,7 +174,9 @@ static struct ctl_table kernel_io_uring_disabled_table[] = {
 		.data		= &sysctl_io_uring_group,
 		.maxlen		= sizeof(gid_t),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_douintvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = &max_gid,
 	},
 	{},
 };
-- 
2.34.1