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Christoph Hellwig b8c3cbca80 driver code: clarify and fix platform device DMA mask allocation 
commit e3a36eb6df upstream.

This does three inter-related things to clarify the usage of the
platform device dma_mask field. In the process, fix the bug introduced
by cdfee56232 ("driver core: initialize a default DMA mask for
platform device") that caused Artem Tashkinov's laptop to not boot with
newer Fedora kernels.

This does:

 - First off, rename the field to "platform_dma_mask" to make it
   greppable.

   We have way too many different random fields called "dma_mask" in
   various data structures, where some of them are actual masks, and
   some of them are just pointers to the mask. And the structures all
   have pointers to each other, or embed each other inside themselves,
   and "pdev" sometimes means "platform device" and sometimes it means
   "PCI device".

   So to make it clear in the code when you actually use this new field,
   give it a unique name (it really should be something even more unique
   like "platform_device_dma_mask", since it's per platform device, not
   per platform, but that gets old really fast, and this is unique
   enough in context).

   To further clarify when the field gets used, initialize it when we
   actually start using it with the default value.

 - Then, use this field instead of the random one-off allocation in
   platform_device_register_full() that is now unnecessary since we now
   already have a perfectly fine allocation for it in the platform
   device structure.

 - The above then allows us to fix the actual bug, where the error path
   of platform_device_register_full() would unconditionally free the
   platform device DMA allocation with 'kfree()'.

   That kfree() was dont regardless of whether the allocation had been
   done earlier with the (now removed) kmalloc, or whether
   setup_pdev_dma_masks() had already been used and the dma_mask pointer
   pointed to the mask that was part of the platform device.

It seems most people never triggered the error path, or only triggered
it from a call chain that set an explicit pdevinfo->dma_mask value (and
thus caused the unnecessary allocation that was "cleaned up" in the
error path) before calling platform_device_register_full().

Robin Murphy points out that in Artem's case the wdat_wdt driver failed
in platform_device_add(), and that was the one that had called
platform_device_register_full() with pdevinfo.dma_mask = 0, and would
have caused that kfree() of pdev.dma_mask corrupting the heap.

A later unrelated kmalloc() then oopsed due to the heap corruption.

Fixes: cdfee56232 ("driver core: initialize a default DMA mask for platform device")
Reported-bisected-and-tested-by:  Artem S. Tashkinov <aros@gmx.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2020-03-18 07:17:56 +01:00
Documentation cifs_atomic_open(): fix double-put on late allocation failure 2020-03-18 07:17:51 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch x86/mce: Fix logic and comments around MSR_PPIN_CTL 2020-03-18 07:17:54 +01:00
block blk-iocost: fix incorrect vtime comparison in iocg_is_idle() 2020-03-18 07:17:52 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: rename sm3-256 to sm3 in hash_algo_name 2020-02-28 17:22:26 +01:00
drivers driver code: clarify and fix platform device DMA mask allocation 2020-03-18 07:17:56 +01:00
fs fscrypt: don't evict dirty inodes after removing key 2020-03-18 07:17:53 +01:00
include driver code: clarify and fix platform device DMA mask allocation 2020-03-18 07:17:56 +01:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel workqueue: don't use wq_select_unbound_cpu() for bound works 2020-03-18 07:17:50 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
mm net: memcg: late association of sock to memcg 2020-03-18 07:17:43 +01:00
net batman-adv: Don't schedule OGM for disabled interface 2020-03-18 07:17:54 +01:00
samples samples/bpf: Set -fno-stack-protector when building BPF programs 2020-02-24 08:36:36 +01:00
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security efi: Only print errors about failing to get certs if EFI vars are found 2020-03-12 13:00:14 +01:00
sound ALSA: hda/realtek - Fixed one of HP ALC671 platform Headset Mic supported 2020-03-18 07:17:38 +01:00
tools ktest: Add timeout for ssh sync testing 2020-03-18 07:17:51 +01:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12 13:00:09 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +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: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile Linux 5.4.25 2020-03-12 13:00:32 +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.