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Tetsuo Handa 72b790c417 fs/open.c: allow opening only regular files during execve()
commit 73601ea5b7 upstream.

syzbot is hitting lockdep warning [1] due to trying to open a fifo
during an execve() operation.  But we don't need to open non regular
files during an execve() operation, for all files which we will need are
the executable file itself and the interpreter programs like /bin/sh and
ld-linux.so.2 .

Since the manpage for execve(2) says that execve() returns EACCES when
the file or a script interpreter is not a regular file, and the manpage
for uselib(2) says that uselib() can return EACCES, and we use
FMODE_EXEC when opening for execve()/uselib(), we can bail out if a non
regular file is requested with FMODE_EXEC set.

Since this deadlock followed by khungtaskd warnings is trivially
reproducible by a local unprivileged user, and syzbot's frequent crash
due to this deadlock defers finding other bugs, let's workaround this
deadlock until we get a chance to find a better solution.

[1] https://syzkaller.appspot.com/bug?id=b5095bfec44ec84213bac54742a82483aad578ce

Link: http://lkml.kernel.org/r/1552044017-7890-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Reported-by: syzbot <syzbot+e93a80c1bb7c5c56e522461c149f8bf55eab1b2b@syzkaller.appspotmail.com>
Fixes: 8924feff66 ("splice: lift pipe_lock out of splice_to_pipe()")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>	[4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-03 06:26:23 +02:00
arch powerpc: bpf: Fix generation of load/store DW instructions 2019-04-03 06:26:21 +02:00
block blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue 2019-03-23 20:09:45 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: testmgr - skip crc32c context test for ahash algorithms 2019-03-23 20:09:55 +01:00
Documentation stable-kernel-rules.rst: add link to networking patch queue 2019-03-23 20:10:10 +01:00
drivers net: dsa: qca8k: remove leftover phy accessors 2019-04-03 06:26:22 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs fs/open.c: allow opening only regular files during execve() 2019-04-03 06:26:23 +02:00
include sctp: get sctphdr by offset in sctp_compute_cksum 2019-04-03 06:26:17 +02:00
init Revert "mm: use early_pfn_to_nid in page_ext_init" 2019-03-23 20:09:46 +01:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel locking/lockdep: Add debug_locks check in __lock_downgrade() 2019-03-27 14:14:43 +09:00
lib rhashtable: Still do rehash when we get EEXIST 2019-04-03 06:26:17 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory.c: do_fault: avoid usage of stale vm_area_struct 2019-03-23 20:10:04 +01:00
net net: sched: fix cleanup NULL pointer exception in act_mirr 2019-04-03 06:26:19 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts kbuild: modversions: Fix relative CRC byte order interpretation 2019-04-03 06:26:23 +02:00
security security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock 2019-03-23 20:10:06 +01:00
sound ALSA: hda/realtek - Fix speakers on Acer Predator Helios 500 Ryzen laptops 2019-04-03 06:26:23 +02:00
tools objtool: Move objtool_file struct off the stack 2019-03-27 14:14:40 +09:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Call kvm_arch_memslots_updated() before updating memslots 2019-03-23 20:10:13 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.32 2019-03-27 14:14:43 +09:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.