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.

Link: https://lkml.kernel.org/r/20250811223740.110392-1-phillip@squashfs.org.uk
Fixes: 734aa85390ea ("Squashfs: check return result of sb_min_blocksize")
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: Scott GUO <scottzhguo@tencent.com>
Closes: https://lore.kernel.org/all/20250811061921.3807353-1-scott_gzh@163.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 992ea0e372572fabd70d29c14fe207ad900c8923..4465cf05603a8f0a6e35a6723f99fb7b27d47969 100644 (file)
--- 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);