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Chris Wilson a22b1a9bb0 drm/i915/display: Check for an LPSP encoder before dereferencing
Avoid a GPF at

<1>[   20.177320] BUG: kernel NULL pointer dereference, address: 000000000000007c
<1>[   20.177322] #PF: supervisor read access in kernel mode
<1>[   20.177323] #PF: error_code(0x0000) - not-present page
<6>[   20.177324] PGD 0 P4D 0
<4>[   20.177327] Oops: 0000 [#1] PREEMPT SMP PTI
<4>[   20.177328] CPU: 1 PID: 944 Comm: debugfs_test Not tainted 5.8.0-rc7-CI-CI_DRM_8814+ #1
<4>[   20.177330] Hardware name: Dell Inc. XPS 13 9360/0823VW, BIOS 2.9.0 07/09/2018
<4>[   20.177372] RIP: 0010:i915_lpsp_capability_show+0x44/0xc0 [i915]
<4>[   20.177374] Code: 0f b6 81 ca 0d 00 00 3c 0b 74 77 76 19 3c 0c 75 44 83 7e 7c 01 7e 2f 48 c7 c6 d7 b9 47 a0 e8 43 df 06 e1 31 c0 c3 3c 09 72 2b <8b> 46 7c 85 c0 75 e6 8b 82 e4 00 00 00 89 c2 83 e2 fb 83 fa 0a 74
<4>[   20.177376] RSP: 0018:ffffc90000cebe38 EFLAGS: 00010246
<4>[   20.177377] RAX: 0000000000000009 RBX: ffff888267fe6a58 RCX: ffff888252d10000
<4>[   20.177378] RDX: ffff88824a9a4000 RSI: 0000000000000000 RDI: ffff888267fe6a30
<4>[   20.177379] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
<4>[   20.177380] R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90000cebf08
<4>[   20.177381] R13: 00000000ffffffff R14: 0000000000000001 R15: ffff888267fe6a30
<4>[   20.177383] FS:  00007f6f9c6b5e40(0000) GS:ffff888276480000(0000) knlGS:0000000000000000
<4>[   20.177384] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[   20.177385] CR2: 000000000000007c CR3: 0000000255f04006 CR4: 00000000003606e0
<4>[   20.177386] Call Trace:
<4>[   20.177390]  seq_read+0xcb/0x420

which is presumably from having no encoder attached at that time.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2175
Fixes: 8806211fe7 ("drm/i915: Add i915_lpsp_capability debugfs")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Animesh Manna <animesh.manna@intel.com>
Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200729130912.30093-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2020-08-17 16:16:31 -04:00
arch Linux 5.8 2020-08-11 11:58:31 +10:00
block block-5.8-2020-07-10 2020-07-10 09:55:46 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto keys: asymmetric: fix error return code in software_key_query() 2020-07-15 15:49:04 -07:00
Documentation Linux 5.8 2020-08-11 11:58:31 +10:00
drivers drm/i915/display: Check for an LPSP encoder before dereferencing 2020-08-17 16:16:31 -04:00
fs io_uring-5.8-2020-07-30 2020-07-30 09:47:07 -07:00
include drm/i915: Remove dubious Valleyview PCI IDs 2020-08-17 16:15:50 -04:00
init kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang 2020-07-02 00:57:45 +09:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-08-01 16:47:24 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-08-01 16:47:24 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm khugepaged: fix null-pointer dereference due to race 2020-07-24 12:42:41 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-08-01 16:47:24 -07:00
samples samples/vfs: avoid warning in statx override 2020-07-03 16:15:25 -07:00
scripts kbuild: remove redundant FORCE definition in scripts/Makefile.modpost 2020-08-02 23:09:16 +09:00
security integrity/ima: switch to using __kernel_read 2020-07-08 08:27:57 +02:00
sound sound fixes for 5.8-final or -rc8 2020-07-31 09:17:24 -07:00
tools Bugfixes and strengthening the validity checks on inputs from new userspace APIs. 2020-08-02 10:41:00 -07:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt kvm: use more precise cast and do not drop __user 2020-07-02 05:39:31 -04:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +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: Do not track defconfig from make savedefconfig 2020-07-05 16:15:46 +09:00
.mailmap mailmap: add entry for Mike Rapoport 2020-07-24 12:42:41 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
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 Linux 5.8 2020-08-11 11:58:31 +10:00
Makefile Linux 5.8 2020-08-02 14:21:45 -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.