linux-kernel - [PATCH] squashfs: fix memory leak in squashfs_fill

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Message-Id: <20250811223740.110392-1-phillip@squashfs.org.uk>
Date: Mon, 11 Aug 2025 23:37:40 +0100
From: Phillip Lougher <phillip@...ashfs.org.uk>
To: akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Cc: Phillip Lougher <phillip@...ashfs.org.uk>,
	Scott GUO <scottzhguo@...cent.com>
Subject: [PATCH] squashfs: fix memory leak in squashfs_fill_super

If sb_min_blocksize returns 0, squashfs_fill_super exits without freeing
allocated memory (sb->s_fs_info).

Fix this by moving the call to sb_min_blocksize to before memory is
allocated.

Fixes: 734aa85390ea ("Squashfs: check return result of sb_min_blocksize")
Reported-by: Scott GUO <scottzhguo@...cent.com>
Closes: https://lore.kernel.org/all/20250811061921.3807353-1-scott_gzh@163.com
Signed-off-by: Phillip Lougher <phillip@...ashfs.org.uk>
---
 fs/squashfs/super.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 992ea0e37257..4465cf05603a 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -187,10 +187,15 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	unsigned short flags;
 	unsigned int fragments;
 	u64 lookup_table_start, xattr_id_table_start, next_table;
-	int err;
+	int err, devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
 
 	TRACE("Entered squashfs_fill_superblock\n");
 
+	if (!devblksize) {
+		errorf(fc, "squashfs: unable to set blocksize\n");
+		return -EINVAL;
+	}
+
 	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
 	if (sb->s_fs_info == NULL) {
 		ERROR("Failed to allocate squashfs_sb_info\n");
@@ -201,12 +206,7 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 
-	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
-	if (!msblk->devblksize) {
-		errorf(fc, "squashfs: unable to set blocksize\n");
-		return -EINVAL;
-	}
-
+	msblk->devblksize = devblksize;
 	msblk->devblksize_log2 = ffz(~msblk->devblksize);
 
 	mutex_init(&msblk->meta_index_mutex);
-- 
2.39.2