linux-kernel - [PATCH v4] ucounts: add missing data type changes

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Date:   Mon, 09 Aug 2021 15:43:56 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Naresh Kamboju <naresh.kamboju@...aro.org>
Cc:     Sven Schnelle <svens@...ux.ibm.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Alexey Gladkov <legion@...nel.org>,
        open list <linux-kernel@...r.kernel.org>,
        LTP List <ltp@...ts.linux.it>, linux-fsdevel@...r.kernel.org,
        Jan Kara <jack@...e.cz>
Subject: [PATCH v4] ucounts: add missing data type changes


commit f9c82a4ea89c3 ("Increase size of ucounts to atomic_long_t")
changed the data type of ucounts/ucounts_max to long, but missed to
adjust a few other places. This is noticeable on big endian platforms
from user space because the /proc/sys/user/max_*_names files all
contain 0.

v4 - Made the min and max constants long so the sysctl values
     are actually settable on little endian machines.
     -- EWB

Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t")
Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
Tested-by: Nathan Chancellor <nathan@...nel.org>
Tested-by: Linux Kernel Functional Testing <lkft@...aro.org>
Acked-by: Alexey Gladkov <legion@...nel.org>
v1: https://lkml.kernel.org/r/20210721115800.910778-1-svens@linux.ibm.com
v2: https://lkml.kernel.org/r/20210721125233.1041429-1-svens@linux.ibm.com
v3: https://lkml.kernel.org/r/20210730062854.3601635-1-svens@linux.ibm.com
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---

Thanks everyone for testing and helping find the cause of this bug.  I
will push this out to linux-next shortly.

 fs/notify/fanotify/fanotify_user.c | 17 +++++++++++------
 fs/notify/inotify/inotify_user.c   | 17 +++++++++++------
 kernel/ucount.c                    | 19 +++++++++++--------
 3 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 64864fb40b40..28b67cb9458d 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -54,22 +54,27 @@ static int fanotify_max_queued_events __read_mostly;
 
 #include <linux/sysctl.h>
 
+static long ft_zero = 0;
+static long ft_int_max = INT_MAX;
+
 struct ctl_table fanotify_table[] = {
 	{
 		.procname	= "max_user_groups",
 		.data	= &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS],
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(long),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra1		= &ft_zero,
+		.extra2		= &ft_int_max,
 	},
 	{
 		.procname	= "max_user_marks",
 		.data	= &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS],
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(long),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra1		= &ft_zero,
+		.extra2		= &ft_int_max,
 	},
 	{
 		.procname	= "max_queued_events",
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 98f61b31745a..62051247f6d2 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -55,22 +55,27 @@ struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
 
 #include <linux/sysctl.h>
 
+static long it_zero = 0;
+static long it_int_max = INT_MAX;
+
 struct ctl_table inotify_table[] = {
 	{
 		.procname	= "max_user_instances",
 		.data		= &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES],
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(long),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra1		= &it_zero,
+		.extra2		= &it_int_max,
 	},
 	{
 		.procname	= "max_user_watches",
 		.data		= &init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES],
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(long),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra1		= &it_zero,
+		.extra2		= &it_int_max,
 	},
 	{
 		.procname	= "max_queued_events",
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 77be3bbe3cc4..bb51849e6375 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -58,14 +58,17 @@ static struct ctl_table_root set_root = {
 	.permissions = set_permissions,
 };
 
-#define UCOUNT_ENTRY(name)				\
-	{						\
-		.procname	= name,			\
-		.maxlen		= sizeof(int),		\
-		.mode		= 0644,			\
-		.proc_handler	= proc_dointvec_minmax,	\
-		.extra1		= SYSCTL_ZERO,		\
-		.extra2		= SYSCTL_INT_MAX,	\
+static long ue_zero = 0;
+static long ue_int_max = INT_MAX;
+
+#define UCOUNT_ENTRY(name)					\
+	{							\
+		.procname	= name,				\
+		.maxlen		= sizeof(long),			\
+		.mode		= 0644,				\
+		.proc_handler	= proc_doulongvec_minmax,	\
+		.extra1		= &ue_zero,			\
+		.extra2		= &ue_int_max,			\
 	}
 static struct ctl_table user_table[] = {
 	UCOUNT_ENTRY("max_user_namespaces"),
-- 
2.20.1