CVS commit: src/sys/dev/acpi

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Apr 12 01:12:03 UTC 2020

Modified Files:
        src/sys/dev/acpi: acpi_ec.c

Log Message:
Reject overly large widths, from mlelstv.

We are returning an ACPI_INTEGER (= uint64_t), so it doesn't make
sense to handle more than 64 bits.

Apparently there are some ACPIs out there that ask for unreasonably
large widths here.  Just reject those requests, rather than writing
past the caller's stack buffer.

Previously we attempted to fix this by copying byte by byte as large
as the caller asked, in order to avoid the undefined behaviour of
shifting past the size of ACPI_INTEGER, but that just turned a shift
(which might have been harmless on real machines) into a stack buffer
overflow (!).

ok msaitoh


To generate a diff of this commit:
cvs rdiff -u -r1.80 -r1.81 src/sys/dev/acpi/acpi_ec.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.