Re: [syzbot] [PATCH] Test oob in squashfs readahead

[syzbot <syzbot+604424eb051c2f696163@syzkaller.appspotmail.com>]

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Subject: [PATCH] Test oob in squashfs readahead
Author: eadavis@qq.com

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 581ce9519339..d335f28c822c 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -323,7 +323,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
 	}
 	if (length < 0 || length > output->length ||
 			(index + length) > msblk->bytes_used) {
-		res = -EIO;
+		res = length < 0 ? -EIO : -EFBIG;
 		goto out;
 	}
 
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ba8c4c50770..5472ddd3596c 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -461,6 +461,11 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
 	TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
 				page->index, squashfs_i(inode)->start);
 
+	if (!file_end) {
+		res = -EINVAL;
+		goto out;
+	}
+
 	if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
 					PAGE_SHIFT))
 		goto out;
@@ -547,6 +552,9 @@ static void squashfs_readahead(struct readahead_control *ractl)
 	int i, file_end = i_size_read(inode) >> msblk->block_log;
 	unsigned int max_pages = 1UL << shift;
 
+	if (!file_end)
+		return;
+
 	readahead_expand(ractl, start, (len | mask) + 1);
 
 	pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);