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Linus Torvalds bc0c4d1e17 mm: check that mm is still valid in madvise()
IORING_OP_MADVISE can end up basically doing mprotect() on the VM of
another process, which means that it can race with our crazy core dump
handling which accesses the VM state without holding the mmap_sem
(because it incorrectly thinks that it is the final user).

This is clearly a core dumping problem, but we've never fixed it the
right way, and instead have the notion of "check that the mm is still
ok" using mmget_still_valid() after getting the mmap_sem for writing in
any situation where we're not the original VM thread.

See commit 04f5866e41 ("coredump: fix race condition between
mmget_not_zero()/get_task_mm() and core dumping") for more background on
this whole mmget_still_valid() thing.  You might want to have a barf bag
handy when you do.

We're discussing just fixing this properly in the only remaining core
dumping routines.  But even if we do that, let's make do_madvise() do
the right thing, and then when we fix core dumping, we can remove all
these mmget_still_valid() checks.

Reported-and-tested-by: Jann Horn <jannh@google.com>
Fixes: c1ca757bd6 ("io_uring: add IORING_OP_MADVISE")
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-24 13:28:03 -07:00
Documentation - Ensure context synchronisation after a write to APIAKey. 2020-04-24 11:34:43 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch - Ensure context synchronisation after a write to APIAKey. 2020-04-24 11:34:43 -07:00
block blk-iocost: Fix error on iocost_ioc_vrate_adj 2020-04-21 09:49:36 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
drivers libata-5.7-2020-04-24 2020-04-24 12:54:13 -07:00
fs io_uring-5.7-2020-04-24 2020-04-24 12:58:22 -07:00
include block-5.7-2020-04-24 2020-04-24 12:44:19 -07:00
init Kbuild updates for v5.7 (2nd) 2020-04-11 09:46:12 -07:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-10 15:36:22 -07:00
kernel A few tracing fixes: 2020-04-24 12:39:21 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-04-16 14:52:29 -07:00
mm mm: check that mm is still valid in madvise() 2020-04-24 13:28:03 -07:00
net Fixes: 2020-04-23 09:33:43 -07:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-21 11:11:56 -07:00
scripts Kbuild fixes for v5.7 2020-04-24 10:39:32 -07:00
security selinux/stable-5.7 PR 20200416 2020-04-16 10:45:47 -07:00
sound sound fixes for 5.7-rc3 2020-04-24 10:27:43 -07:00
tools linux-kselftest-5.7-rc3 2020-04-22 10:47:49 -07:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt KVM: Pass kvm_init()'s opaque param to additional arch funcs 2020-03-31 10:48:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-04-18 13:49:33 +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: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.mailmap mailmap: Add Sedat Dilek (replacement for expired email address) 2020-04-11 09:28:34 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS pci-v5.7-fixes-1 2020-04-23 11:04:59 -07:00
Makefile Linux 5.7-rc2 2020-04-19 14:35:30 -07:00
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.