erofs: fix shift-out-of-bounds of blkszbits

commit bde545295b710bdd13a0fcd4b9fddd2383eeeb3a upstream.

syzbot generated a crafted bitszbits which can be shifted
out-of-bounds[1]. So directly print unsupported blkszbits
instead of blksize.

[1] https://lore.kernel.org/r/000000000000c72ddd05b9444d2f@google.com

Link: https://lore.kernel.org/r/20210120013016.14071-1-hsiangkao@aol.com
Reported-by: syzbot+c68f467cd7c45860e8d4@syzkaller.appspotmail.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index be10b16..d5a6b9b 100644 (file)
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -158,8 +158,8 @@ static int erofs_read_superblock(struct super_block *sb)
        blkszbits = dsb->blkszbits;
        /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
        if (blkszbits != LOG_BLOCK_SIZE) {
-               erofs_err(sb, "blksize %u isn't supported on this platform",
-                         1 << blkszbits);
+               erofs_err(sb, "blkszbits %u isn't supported on this platform",
+                         blkszbits);
                goto out;
        }