Linmao Li 9f0ee411fc drm/vc4: Prevent shader BO mappings from becoming writable
commit 0c9e636763 upstream.

vc4_gem_object_mmap() rejects a writable mapping of a validated shader
BO, but leaves VM_MAYWRITE set.  Userspace can map the BO read-only and
then turn it writable with mprotect().

Validated shader BOs must stay read-only: the validator checks the
instructions once and the GPU trusts them afterwards.  A writable
mapping lets userspace rewrite the code after validation, bypassing the
validator.

Clear VM_MAYWRITE on the read-only path so the mapping cannot be
upgraded, as i915 already does for its read-only objects.

Fixes: 463873d570 ("drm/vc4: Add an API for creating GPU shaders in GEM BOs.")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/dri-devel/20260720085554.B0AF01F000E9@smtp.kernel.org/
Signed-off-by: Linmao Li <lilinmao@kylinos.cn>
Link: https://patch.msgid.link/20260721011558.1672477-1-lilinmao@kylinos.cn
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-03 11:15:25 +02:00
2026-07-24 16:03:06 +02:00
2026-05-23 13:03:09 +02:00
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2026-05-23 13:03:09 +02:00
2026-07-30 13:02:12 +02:00
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Linux kernel
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There are several guides for kernel developers and users. These guides can
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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
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