The patch titled Subject: Squashfs: reject negative file sizes in squashfs_read_inode() has been added to the -mm mm-nonmm-unstable branch. Its filename is squashfs-reject-negative-file-sizes-in-squashfs_read_inode.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Phillip Lougher phillip@squashfs.org.uk Subject: Squashfs: reject negative file sizes in squashfs_read_inode() Date: Fri, 26 Sep 2025 22:59:35 +0100

Syskaller reports a "WARNING in ovl_copy_up_file" in overlayfs.

This warning is ultimately caused because the underlying Squashfs file system returns a file with a negative file size.

This commit checks for a negative file size and returns EINVAL.

Link: https://lkml.kernel.org/r/20250926215935.107233-1-phillip@squashfs.org.uk Fixes: 6545b246a2c8 ("Squashfs: inode operations") Signed-off-by: Phillip Lougher phillip@squashfs.org.uk Reported-by: syzbot+f754e01116421e9754b9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68d580e5.a00a0220.303701.0019.GAE@google.com/ Cc: Amir Goldstein amir73il@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/squashfs/inode.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-)

--- a/fs/squashfs/inode.c~squashfs-reject-negative-file-sizes-in-squashfs_read_inode +++ a/fs/squashfs/inode.c @@ -145,6 +145,10 @@ int squashfs_read_inode(struct inode *in goto failed_read;

inode->i_size = le32_to_cpu(sqsh_ino->file_size); + if (inode->i_size < 0) { + err = -EINVAL; + goto failed_read; + } frag = le32_to_cpu(sqsh_ino->fragment); if (frag != SQUASHFS_INVALID_FRAG) { /* @@ -197,6 +201,10 @@ int squashfs_read_inode(struct inode *in goto failed_read;

inode->i_size = le64_to_cpu(sqsh_ino->file_size); + if (inode->i_size < 0) { + err = -EINVAL; + goto failed_read; + } frag = le32_to_cpu(sqsh_ino->fragment); if (frag != SQUASHFS_INVALID_FRAG) { /* @@ -249,8 +257,12 @@ int squashfs_read_inode(struct inode *in if (err < 0) goto failed_read;

- set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); inode->i_size = le16_to_cpu(sqsh_ino->file_size); + if (inode->i_size < 0) { + err = -EINVAL; + goto failed_read; + } + set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); inode->i_op = &squashfs_dir_inode_ops; inode->i_fop = &squashfs_dir_ops; inode->i_mode |= S_IFDIR; @@ -273,9 +285,13 @@ int squashfs_read_inode(struct inode *in if (err < 0) goto failed_read;

+ inode->i_size = le32_to_cpu(sqsh_ino->file_size); + if (inode->i_size < 0) { + err = -EINVAL; + goto failed_read; + } xattr_id = le32_to_cpu(sqsh_ino->xattr); set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); - inode->i_size = le32_to_cpu(sqsh_ino->file_size); inode->i_op = &squashfs_dir_inode_ops; inode->i_fop = &squashfs_dir_ops; inode->i_mode |= S_IFDIR; @@ -302,7 +318,7 @@ int squashfs_read_inode(struct inode *in goto failed_read;

inode->i_size = le32_to_cpu(sqsh_ino->symlink_size); - if (inode->i_size > PAGE_SIZE) { + if (inode->i_size < 0 || inode->i_size > PAGE_SIZE) { ERROR("Corrupted symlink\n"); return -EINVAL; } _

Patches currently in -mm which might be from phillip@squashfs.org.uk are

squashfs-fix-uninit-value-in-squashfs_get_parent.patch squashfs-add-additional-inode-sanity-checking.patch squashfs-add-seek_data-seek_hole-support.patch squashfs-reject-negative-file-sizes-in-squashfs_read_inode.patch