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7dd670db9a
Check in snd_intel_dsp_check_soundwire() that the pointer returned by
ACPI_HANDLE() is not NULL, before passing it on to other functions.
The original code assumed a non-NULL return, but if it was unexpectedly
NULL it would end up passed to acpi_walk_namespace() as the start
point, and would result in
[ 3.219028] BUG: kernel NULL pointer dereference, address:
0000000000000018
[ 3.219029] #PF: supervisor read access in kernel mode
[ 3.219030] #PF: error_code(0x0000) - not-present page
[ 3.219031] PGD 0 P4D 0
[ 3.219032] Oops: Oops: 0000 [#1] SMP NOPTI
[ 3.219035] CPU: 2 UID: 0 PID: 476 Comm: (udev-worker) Tainted: G S
AW E 6.17.0-rc5-test #1 PREEMPT(voluntary)
[ 3.219038] Tainted: [S]=CPU_OUT_OF_SPEC, [A]=OVERRIDDEN_ACPI_TABLE,
[W]=WARN, [E]=UNSIGNED_MODULE
[ 3.219040] RIP: 0010:acpi_ns_walk_namespace+0xb5/0x480
This problem was triggered by a bugged DSDT that the kernel couldn't parse.
But it shouldn't be possible to SEGFAULT the kernel just because of some
bugs in ACPI.
Fixes: 0650857570 ("ALSA: hda: add autodetection for SoundWire")
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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 reStructuredText 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.