Michael Bommarito
91602ba3c2
commit 24376458138387fb251e782e624c7776e9826796 upstream.
isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker-
controlled block number (ifid->block or ifid->parent_block) from
the NFS file handle to isofs_export_iget(), which only rejects
block == 0 before calling isofs_iget() and ultimately sb_bread().
A crafted file handle with fh_len sufficient to pass the check
added by commit 0405d4b63d08 ("isofs: Prevent the use of too small
fid") can still drive the server to read any in-range block on the
backing device as if it were an iso_directory_record. That earlier
fix was assigned CVE-2025-37780.
sb_bread() on an out-of-range block returns NULL cleanly via the
EIO path, so there is no memory-safety violation. For in-range
reads of adjacent-partition data on the same block device, the
unrelated bytes end up in iso_inode_info fields that reach the NFS
client as dentry metadata. The deployment surface (isofs exported
over NFS from loop-mounted images) is narrow and requires an
authenticated NFS peer, but the malformed-file-handle class is
reportable as hardening next to the existing CVE-2025-37780 fix.
Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so
the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent()
call sites with a single line.
Fixes: 0405d4b63d08 ("isofs: Prevent the use of too small fid")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Link: https://patch.msgid.link/20260419212155.2169382-3-michael.bommarito@gmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.