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Stephen Brennan 0766ec82e5 namei: Fix use after free in kern_path_locked
In 0ee50b4753 ("namei: change filename_parentat() calling
conventions"), filename_parentat() was made to always call putname() on
the  filename before returning, and kern_path_locked() was migrated to
this calling convention.  However, kern_path_locked() uses the "last"
parameter to lookup and potentially create a new dentry. The last
parameter contains the last component of the path and points within the
filename, which was recently freed at the end of filename_parentat().
Thus, when kern_path_locked() calls __lookup_hash(), it is using the
filename after it has already been freed.

In other words, these calling conventions had been wrong for the
only remaining caller of filename_parentat().  Everything else
is using __filename_parentat(), which does not drop the reference;
so should kern_path_locked().

Switch kern_path_locked() to use of __filename_parentat() and move
getting/dropping struct filename into wrapper.  Remove filename_parentat(),
now that we have no remaining callers.

Fixes: 0ee50b4753 ("namei: change filename_parentat() calling conventions")
Link: https://lore.kernel.org/linux-fsdevel/YS9D4AlEsaCxLFV0@infradead.org/
Link: https://lore.kernel.org/linux-fsdevel/YS+csMTV2tTXKg3s@zeniv-ca.linux.org.uk/
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: syzbot+fb0d60a179096e8c2731@syzkaller.appspotmail.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Co-authored-by: Dmitry Kadashev <dkadashev@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2021-09-07 15:56:16 -04:00
arch Tracing updates for 5.15: 2021-09-05 11:50:41 -07:00
block block-5.15-2021-09-05 2021-09-06 10:06:26 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation Tracing updates for 5.15: 2021-09-05 11:50:41 -07:00
drivers thunderbolt: test: split up test cases in tb_test_credit_alloc_all 2021-09-06 12:27:03 -07:00
fs namei: Fix use after free in kern_path_locked 2021-09-07 15:56:16 -04:00
include libata-5.15-2021-09-05 2021-09-06 09:51:42 -07:00
init Enable '-Werror' by default for all kernel builds 2021-09-05 11:24:05 -07:00
ipc memcg: enable accounting of ipc resources 2021-09-03 09:58:12 -07:00
kernel Tracing updates for 5.15: 2021-09-05 11:50:41 -07:00
lib lib/test_scanf: split up number parsing test routines 2021-09-06 11:04:03 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux 2021-09-04 11:35:47 -07:00
net NFS Client Updates for Linux 5.15 2021-09-04 10:25:26 -07:00
samples VFIO update for v5.15-rc1 2021-09-02 13:41:33 -07:00
scripts don't make the syscall checking produce errors from warnings 2021-09-06 09:15:09 -07:00
security Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
sound Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
tools perf tools changes for v5.15: 2021-09-05 11:56:18 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-04 06:02:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update email address of Matthias Fuchs and Thomas Körper 2021-08-19 09:39:44 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
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 misc-5.15-2021-09-05 2021-09-06 10:00:25 -07:00
Makefile Enable '-Werror' by default for all kernel builds 2021-09-05 11:24:05 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.