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779aa4d747
Trying to build parisc:allmodconfig with gcc 12.x or later results
in the following build error.
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32 overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
161 | memcpy(data, args->mthd.data, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56 overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
298 | memcpy(data, args->new.data, size);
gcc assumes that 'sizeof(*args) + size' can overflow, which would result
in the problem.
The problem is not new, only it is now no longer a warning but an error
since W=1 has been enabled for the drm subsystem and since Werror is
enabled for test builds.
Rearrange arithmetic and use check_add_overflow() for validating the
allocation size to avoid the overflow. While at it, split assignments
out of if conditions.
Fixes: a61ddb4393 ("drm: enable (most) W=1 warnings by default across the subsystem")
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Joe Perches <joe@perches.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240524134817.1369993-1-linux@roeck-us.net
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.