memfd: pass argument of memfd_fcntl as int

The interface for fcntl expects the argument passed for the command
F_ADD_SEALS to be of type int.  The current code wrongly treats it as a
long.  In order to avoid access to undefined bits, we should explicitly
cast the argument to int.

This commit changes the signature of all the related and helper functions
so that they treat the argument as int instead of long.

Link: https://lkml.kernel.org/r/20230414152459.816046-5-Luca.Vizzarro@arm.com
Signed-off-by: Luca Vizzarro <Luca.Vizzarro@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Kevin Brodsky <Kevin.Brodsky@arm.com>
Cc: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: David Laight <David.Laight@ACULAB.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/memfd.h b/include/linux/memfd.h
index 4f1600413f916e9c606a8fb338dd4dd1dd607ee6..e7abf6fa4c522324cc14091b4833f11586356cee 100644 (file)
--- a/include/linux/memfd.h
+++ b/include/linux/memfd.h
@@ -5,9 +5,9 @@
 #include <linux/file.h>
 
 #ifdef CONFIG_MEMFD_CREATE
-extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg);
+extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg);
 #else
-static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned long a)
+static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned int a)
 {
        return -EINVAL;
 }

diff --git a/mm/memfd.c b/mm/memfd.c
index a0a7a37e81771b38549f2f0b0d3d5f63cdeed587..69b90c31d38cedb03d7e387ae2b7eb976128df8e 100644 (file)
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -243,16 +243,12 @@ static int memfd_get_seals(struct file *file)
        return seals ? *seals : -EINVAL;
 }
 
-long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg)
 {
        long error;
 
        switch (cmd) {
        case F_ADD_SEALS:
-               /* disallow upper 32bit */
-               if (arg > UINT_MAX)
-                       return -EINVAL;
-
                error = memfd_add_seals(file, arg);
                break;
        case F_GET_SEALS: