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Hawkins Jiawei 9a8862820c hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param()
[ Upstream commit 26215b7ee9 ]

Syzkaller reports a null-ptr-deref bug as follows:
======================================================
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:hugetlbfs_parse_param+0x1dd/0x8e0 fs/hugetlbfs/inode.c:1380
[...]
Call Trace:
 <TASK>
 vfs_parse_fs_param fs/fs_context.c:148 [inline]
 vfs_parse_fs_param+0x1f9/0x3c0 fs/fs_context.c:129
 vfs_parse_fs_string+0xdb/0x170 fs/fs_context.c:191
 generic_parse_monolithic+0x16f/0x1f0 fs/fs_context.c:231
 do_new_mount fs/namespace.c:3036 [inline]
 path_mount+0x12de/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
 [...]
 </TASK>
======================================================

According to commit "vfs: parse: deal with zero length string value",
kernel will set the param->string to null pointer in vfs_parse_fs_string()
if fs string has zero length.

Yet the problem is that, hugetlbfs_parse_param() will dereference the
param->string, without checking whether it is a null pointer.  To be more
specific, if hugetlbfs_parse_param() parses an illegal mount parameter,
such as "size=,", kernel will constructs struct fs_parameter with null
pointer in vfs_parse_fs_string(), then passes this struct fs_parameter to
hugetlbfs_parse_param(), which triggers the above null-ptr-deref bug.

This patch solves it by adding sanity check on param->string
in hugetlbfs_parse_param().

Link: https://lkml.kernel.org/r/20221020231609.4810-1-yin31149@gmail.com
Reported-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com
Tested-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com
  Link: https://lore.kernel.org/all/0000000000005ad00405eb7148c6@google.com/
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hawkins Jiawei <yin31149@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:14:44 +01:00
Documentation overflow: Implement size_t saturating arithmetic helpers 2022-12-31 13:14:33 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch x86/hyperv: Remove unregister syscore call from Hyper-V cleanup 2022-12-31 13:14:39 +01:00
block blk-mq: fix possible memleak when register 'hctx' failed 2022-12-31 13:14:43 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: tcrypt - Fix multibuffer skcipher speed test mem leak 2022-12-31 13:14:24 +01:00
drivers scsi: elx: libefc: Fix second parameter type in state callbacks 2022-12-31 13:14:44 +01:00
fs hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param() 2022-12-31 13:14:44 +01:00
include media: dvbdev: adopts refcnt to avoid UAF 2022-12-31 13:14:43 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-02 17:41:08 +01:00
io_uring io_uring: Fix a null-ptr-deref in io_tctx_exit_cb() 2022-12-14 11:37:31 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel bpf: Prevent decl_tag from being referenced in func_proto arg 2022-12-31 13:14:42 +01:00
lib overflow: Implement size_t saturating arithmetic helpers 2022-12-31 13:14:33 +01:00
mm mm/gup: fix gup_pud_range() for dax 2022-12-14 11:37:20 +01:00
net ethtool: avoiding integer overflow in ethtool_phys_id() 2022-12-31 13:14:42 +01:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2022-12-31 13:14:31 +01:00
scripts scripts/faddr2line: Fix regression in name resolution on ppc64le 2022-12-08 11:28:38 +01:00
security apparmor: Fix memleak in alloc_ns() 2022-12-31 13:14:22 +01:00
sound ASoC: codecs: rt298: Add quirk for KBL-R RVP platform 2022-12-31 13:14:40 +01:00
tools libbpf: Avoid enum forward-declarations in public API in C++ mode 2022-12-31 13:14:43 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt kvm: Add support for arch compat vm ioctls 2022-10-29 10:12:54 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 futex: Move to kernel/futex/ 2022-12-31 13:14:04 +01:00
Makefile Linux 5.15.85 2022-12-21 17:36:38 +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.