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40f6090d6e
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Randy Dunlap 40f6090d6e JFS: more checks for invalid superblock 
commit 3bef198f1b upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-07 12:34:04 +01:00
arch x86/build: Treat R_386_PLT32 relocation as R_386_PC32 2021-03-07 12:34:04 +01:00
block blk-settings: align max_sectors on "logical_block_size" boundary 2021-03-04 11:38:22 +01:00
certs certs: Fix blacklist flag type confusion 2021-03-04 11:37:59 +01:00
crypto crypto: michael_mic - fix broken misalignment handling 2021-03-04 11:38:31 +01:00
Documentation mm/vmscan: restore zone_reclaim_mode ABI 2021-03-04 11:38:38 +01:00
drivers drm/virtio: use kvmalloc for large allocations 2021-03-07 12:34:04 +01:00
fs JFS: more checks for invalid superblock 2021-03-07 12:34:04 +01:00
include net_sched: fix RTNL deadlock again caused by request_module() 2021-03-04 11:38:47 +01:00
init kgdb: fix to kill breakpoints on initmem after boot 2021-03-04 11:38:46 +01:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel kgdb: fix to kill breakpoints on initmem after boot 2021-03-04 11:38:46 +01:00
lib udp: fix skb_copy_and_csum_datagram with odd segment sizes 2021-02-17 11:02:28 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm, compaction: make fast_isolate_freepages() stay within zone 2021-03-04 11:38:38 +01:00
net net_sched: fix RTNL deadlock again caused by request_module() 2021-03-04 11:38:47 +01:00
samples watch_queue: Drop references to /dev/watch_queue 2021-03-04 11:37:59 +01:00
scripts scripts/recordmcount.pl: support big endian for ARCH sh 2021-02-26 10:13:02 +01:00
security KEYS: trusted: Reserve TPM for seal and unseal operations 2021-03-04 11:38:29 +01:00
sound ASoC: siu: Fix build error by a wrong const prefix 2021-03-04 11:38:28 +01:00
tools wireguard: selftests: test multiple parallel streams 2021-03-04 11:38:47 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() 2021-02-26 10:13:01 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-12-10 15:30:13 -08:00
Makefile Linux 5.10.20 2021-03-04 11:38:47 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.