linux-kernel - [PATCH] fs/nilfs2: copy userspace-array safely

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Message-ID: <20231102183751.47413-1-pstanner@redhat.com>
Date:   Thu,  2 Nov 2023 19:37:51 +0100
From:   Philipp Stanner <pstanner@...hat.com>
To:     Ryusuke Konishi <konishi.ryusuke@...il.com>
Cc:     linux-nilfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Philipp Stanner <pstanner@...hat.com>,
        Dave Airlie <airlied@...hat.com>
Subject: [PATCH] fs/nilfs2: copy userspace-array safely

ioctl.c utilizes memdup_user() to copy a userspace array. This is done
without an overflow-check.

Use the new wrapper memdup_array_user() to copy the array more safely.

Suggested-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Philipp Stanner <pstanner@...hat.com>
---
Linus recently merged this new wrapper for Kernel v6.7
---
 fs/nilfs2/ioctl.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 40ffade49f38..6a9dceebb18d 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -877,11 +877,11 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
 
 	/*
 	 * argv[4] points to segment numbers this ioctl cleans.  We
-	 * use kmalloc() for its buffer because memory used for the
-	 * segment numbers is enough small.
+	 * use kmalloc() for its buffer because the memory used for the
+	 * segment numbers is small enough.
 	 */
-	kbufs[4] = memdup_user((void __user *)(unsigned long)argv[4].v_base,
-			       nsegs * sizeof(__u64));
+	kbufs[4] = memdup_array_user((void __user *)(unsigned long)argv[4].v_base,
+				     nsegs, sizeof(__u64));
 	if (IS_ERR(kbufs[4])) {
 		ret = PTR_ERR(kbufs[4]);
 		goto out;
-- 
2.41.0