5.4-stable review patch. If anyone has any objections, please let me know.
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From: Jani Nikula jani.nikula@intel.com
commit 2e43ae7dd71cd9bb0d1bce1d3306bf77523feb81 upstream.
Initializing const char opregion_signature[16] = OPREGION_SIGNATURE (which is "IntelGraphicsMem") drops the NUL termination of the string. This is intentional, but the compiler doesn't know this.
Switch to initializing header->signature directly from the string litaral, with sizeof destination rather than source. We don't treat the signature as a string other than for initialization; it's really just a blob of binary data.
Add a static assert for good measure to cross-check the sizes.
Reported-by: Kees Cook kees@kernel.org Closes: https://lore.kernel.org/r/20250310222355.work.417-kees@kernel.org Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13934 Tested-by: Nicolas Chauvet kwizart@gmail.com Tested-by: Damian Tometzki damian@riscv-rocks.de Cc: stable@vger.kernel.org Reviewed-by: Zhenyu Wang zhenyuw.linux@gmail.com Link: https://lore.kernel.org/r/20250327124739.2609656-1-jani.nikula@intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com (cherry picked from commit 4f8207469094bd04aad952258ceb9ff4c77b6bfa) Signed-off-by: Jani Nikula jani.nikula@intel.com [nathan: Move static_assert() to top of function to avoid instance of -Wdeclaration-after-statement due to lack of b5ec6fd286df] Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/i915/gvt/opregion.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/gvt/opregion.c +++ b/drivers/gpu/drm/i915/gvt/opregion.c @@ -223,7 +223,8 @@ int intel_vgpu_init_opregion(struct inte u8 *buf; struct opregion_header *header; struct vbt v; - const char opregion_signature[16] = OPREGION_SIGNATURE; + + static_assert(sizeof(header->signature) == sizeof(OPREGION_SIGNATURE) - 1);
gvt_dbg_core("init vgpu%d opregion\n", vgpu->id); vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_KERNEL | @@ -237,8 +238,9 @@ int intel_vgpu_init_opregion(struct inte /* emulated opregion with VBT mailbox only */ buf = (u8 *)vgpu_opregion(vgpu)->va; header = (struct opregion_header *)buf; - memcpy(header->signature, opregion_signature, - sizeof(opregion_signature)); + + memcpy(header->signature, OPREGION_SIGNATURE, sizeof(header->signature)); + header->size = 0x8; header->opregion_ver = 0x02000000; header->mboxes = MBOX_VBT;