3bef198f1b
syzbot is feeding invalid superblock data to JFS for mount testing. JFS does not check several of the fields -- just assumes that they are good since the JFS_MAGIC and version fields are good. In this case (syzbot reproducer), we have s_l2bsize == 0xda0c, pad == 0xf045, and s_state == 0x50, all of which are invalid IMO. Having s_l2bsize == 0xda0c causes this UBSAN warning: UBSAN: shift-out-of-bounds in fs/jfs/jfs_mount.c:373:25 shift exponent -9716 is negative s_l2bsize can be tested for correctness. pad can be tested for non-0 and punted. s_state can be tested for its valid values and punted. Do those 3 tests and if any of them fails, report the superblock as invalid/corrupt and let fsck handle it. With this patch, chkSuper() says this when JFS_DEBUG is enabled: jfs_mount: Mount Failure: superblock is corrupt! Mount JFS Failure: -22 jfs_mount failed w/return code = -22 The obvious problem with this method is that next week there could be another syzbot test that uses different fields for invalid values, this making this like a game of whack-a-mole. syzkaller link: https://syzkaller.appspot.com/bug?extid=36315852ece4132ec193 Reported-by: syzbot+36315852ece4132ec193@syzkaller.appspotmail.com Reported-by: kernel test robot <lkp@intel.com> # v2 Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com> Cc: jfs-discussion@lists.sourceforge.net |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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.
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.