7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Rapoport (Microsoft) [ Upstream commit ea6fd393cb9e6811a748c7551de0dd3090f9dcde ] Nathan Chancellor reports the following warning: CPA detected W^X violation: 8000000000000123 -> 0000000000000123 range: 0xffffffffc0400000 - 0xffffffffc0400fff PFN 100e00 from its_alloc() doing set_memory_x() during early retpoline setup. The warning is not factually wrong but it is unproductive. First, the RWX permission is temporary and fixed up by execmem_restore_rox(). Second, at the time of the warning, all kernel text is mapped RWX. So there is not even a transient actual security issue. The right way to fix this up is to relax RWX detection during boot but make a final verification pass over all kernel page tables before running userspace. There is code to do that today (debug_checkwx()) but it must be enabled explicitly in Kconfig. For now, retain the warning even if it's unproductive, but make it scream less loudly: use pr_warn_once() rather than WARN_ONCE(). Remove the warning once debug_checkwx() behavior becomes unconditional. Closes: https://lore.kernel.org/all/20260905044253.GA3816371@ax162 Reported-by: Nathan Chancellor Signed-off-by: Mike Rapoport (Microsoft) Signed-off-by: Dave Hansen Tested-by: Nathan Chancellor Tested-by: Ihor Solodrai Link: https://patch.msgid.link/20260913-fixes-verify-rwx-v3-1-5e1d6a08bd02@kernel.org Signed-off-by: Sasha Levin --- arch/x86/mm/pat/set_memory.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 226660973d515..c71f6774a2f32 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -719,6 +719,21 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star return new; end = start + npg * PAGE_SIZE - 1; + + /* + * If the kernel text is still RWX, gently complain, this could be a + * false positive. + * Once debug_checkwx() becomes mandatory for CONFIG_STRICT_KERNEL_RWX, + * the warning can be removed completely. + */ + if (!kernel_set_to_readonly) { + pr_warn_once("CPA detected W^X violation: %016llx -> %016llx range: 0x%016lx - 0x%016lx PFN %lx\n", + (unsigned long long)pgprot_val(old), + (unsigned long long)pgprot_val(new), + start, end, pfn); + return new; + } + WARN_ONCE(1, "CPA detected W^X violation: %016llx -> %016llx range: 0x%016lx - 0x%016lx PFN %lx\n", (unsigned long long)pgprot_val(old), (unsigned long long)pgprot_val(new), -- 2.53.0