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..ba4f53c3725d 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -321,11 +321,16 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
 		TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
 		      compressed ? "" : "un", length);
 	}
-	if (length < 0 || length > output->length ||
-			(index + length) > msblk->bytes_used) {
+
+	if (length < 0) {
 		res = -EIO;
 		goto out;
 	}
+	if (length > output->length || (index + length) > msblk->bytes_used) {
+		printk("srd: l:%d, ol: %d, bu: %d,i:%d, c:%d \n", length, 
+				output->length, msblk->bytes_used, index, compressed);
+		length = min_t(int, msblk->bytes_used - index, output->length);
+	}
 
 	if (next_index)
 		*next_index = index + length;
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ba8c4c50770..b54d6b993357 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -461,6 +461,12 @@ 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) {
+		printk("i:%p, is:%d, %s\n", inode, i_size_read(inode), __func__);
+		res = -EINVAL;
+		goto out;
+	}
+
 	if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
 					PAGE_SHIFT))
 		goto out;
@@ -547,6 +553,11 @@ 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 && !start) {
+		printk("i:%p, is:%d, %s\n", inode, i_size_read(inode), __func__);
+		return;
+	}
+
 	readahead_expand(ractl, start, (len | mask) + 1);
 
 	pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
index aa3411354e66..f3b0111e6fbd 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -175,6 +175,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		u64 frag_blk;
 		struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;
 
+		printk("in0: %p, fs: %d, it: %d, %s\n", inode, inode->i_size, type, __func__);
 		err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 							sizeof(*sqsh_ino));
 		if (err < 0)
@@ -403,6 +404,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 	} else
 		squashfs_i(inode)->xattr_count = 0;
 
+	printk("in: %p, fs: %d, it: %d, %s\n", inode, inode->i_size, type, __func__);
 	return 0;
 
 failed_read: