linux-kernel - [PATCH v2] ARM: mm: Don't use %pK through printk

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Message-Id: <20250811-restricted-pointers-arm-v2-1-74bac42f3699@linutronix.de>
Date: Mon, 11 Aug 2025 12:49:01 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Russell King <linux@...linux.org.uk>, Kees Cook <kees@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
 linux-hardening@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH v2] ARM: mm: Don't use %pK through printk

Restricted pointers ("%pK") were never meant to be used
through printk(). They can acquire sleeping locks in atomic contexts.

Switch to %px over the more secure %p as this usage is a debugging aid,
gated behind CONFIG_DEBUG_VIRTUAL and used by WARN().

Link: https://lore.kernel.org/lkml/20250113171731-dc10e3c1-da64-4af0-b767-7c7070468023@linutronix.de/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
Changes in v2:
- Rebase on v6.17-rc1
- Switch to %px instead
- Link to v1: https://lore.kernel.org/r/20250217-restricted-pointers-arm-v1-1-aaa0fb22e18c@linutronix.de
---
 arch/arm/mm/physaddr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/physaddr.c b/arch/arm/mm/physaddr.c
index 3f263c840ebc462e13c34d33be0161e7a473173d..1a37ebfacbba969b9341fe17518cdd81fb2899b6 100644
--- a/arch/arm/mm/physaddr.c
+++ b/arch/arm/mm/physaddr.c
@@ -38,7 +38,7 @@ static inline bool __virt_addr_valid(unsigned long x)
 phys_addr_t __virt_to_phys(unsigned long x)
 {
 	WARN(!__virt_addr_valid(x),
-	     "virt_to_phys used for non-linear address: %pK (%pS)\n",
+	     "virt_to_phys used for non-linear address: %px (%pS)\n",
 	     (void *)x, (void *)x);

 	return __virt_to_phys_nodebug(x);

---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250217-restricted-pointers-arm-07493b11c0fc

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>