From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Mon, 13 Oct 2025 22:11:49 +0000 (-0400)
Subject: Squashfs: add additional inode sanity checking
X-Git-Tag: v5.4.301~88
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5b5cd739c54daae470dacf7af87366d87566dfa1;p=thirdparty%2Fkernel%2Fstable.git

Squashfs: add additional inode sanity checking

[ Upstream commit 9ee94bfbe930a1b39df53fa2d7b31141b780eb5a ]

Patch series "Squashfs: performance improvement and a sanity check".

This patchset adds an additional sanity check when reading regular file
inodes, and adds support for SEEK_DATA/SEEK_HOLE lseek() whence values.

This patch (of 2):

Add an additional sanity check when reading regular file inodes.

A regular file if the file size is an exact multiple of the filesystem
block size cannot have a fragment.  This is because by definition a
fragment block stores tailends which are not a whole block in size.

Link: https://lkml.kernel.org/r/20250923220652.568416-1-phillip@squashfs.org.uk
Link: https://lkml.kernel.org/r/20250923220652.568416-2-phillip@squashfs.org.uk
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 9f1c14c1de1b ("Squashfs: reject negative file sizes in squashfs_read_inode()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
index c381d08c30c2..b0a5ce62dae4 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -140,8 +140,17 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		if (err < 0)
 			goto failed_read;
 
+		inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 		frag = le32_to_cpu(sqsh_ino->fragment);
 		if (frag != SQUASHFS_INVALID_FRAG) {
+			/*
+			 * the file cannot have a fragment (tailend) and have a
+			 * file size a multiple of the block size
+			 */
+			if ((inode->i_size & (msblk->block_size - 1)) == 0) {
+				err = -EINVAL;
+				goto failed_read;
+			}
 			frag_offset = le32_to_cpu(sqsh_ino->offset);
 			frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 			if (frag_size < 0) {
@@ -155,7 +164,6 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		}
 
 		set_nlink(inode, 1);
-		inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 		inode->i_fop = &generic_ro_fops;
 		inode->i_mode |= S_IFREG;
 		inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
@@ -184,8 +192,17 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		if (err < 0)
 			goto failed_read;
 
+		inode->i_size = le64_to_cpu(sqsh_ino->file_size);
 		frag = le32_to_cpu(sqsh_ino->fragment);
 		if (frag != SQUASHFS_INVALID_FRAG) {
+			/*
+			 * the file cannot have a fragment (tailend) and have a
+			 * file size a multiple of the block size
+			 */
+			if ((inode->i_size & (msblk->block_size - 1)) == 0) {
+				err = -EINVAL;
+				goto failed_read;
+			}
 			frag_offset = le32_to_cpu(sqsh_ino->offset);
 			frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 			if (frag_size < 0) {
@@ -200,7 +217,6 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 
 		xattr_id = le32_to_cpu(sqsh_ino->xattr);
 		set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
-		inode->i_size = le64_to_cpu(sqsh_ino->file_size);
 		inode->i_op = &squashfs_inode_ops;
 		inode->i_fop = &generic_ro_fops;
 		inode->i_mode |= S_IFREG;