linux-kernel - [v2 PATCH] arm64: mm: make linear mapping permission update more robust for patial range

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20251023204428.477531-1-yang@os.amperecomputing.com>
Date: Thu, 23 Oct 2025 13:44:28 -0700
From: Yang Shi <yang@...amperecomputing.com>
To: ryan.roberts@....com,
	dev.jain@....com,
	cl@...two.org,
	catalin.marinas@....com,
	will@...nel.org
Cc: yang@...amperecomputing.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [v2 PATCH] arm64: mm: make linear mapping permission update more robust for patial range

The commit fcf8dda8cc48 ("arm64: pageattr: Explicitly bail out when changing
permissions for vmalloc_huge mappings") made permission update for
partial range more robust. But the linear mapping permission update
still assumes update the whole range by iterating from the first page
all the way to the last page of the area.

Make it more robust by updating the linear mapping permission from the
page mapped by start address, and update the number of numpages.

Reviewed-by: Ryan Roberts <ryan.roberts@....com>
Reviewed-by: Dev Jain <dev.jain@....com>
Signed-off-by: Yang Shi <yang@...amperecomputing.com>
---
v2: * Dropped the fixes tag per Ryan and Dev
    * Simplified the loop per Dev
    * Collected R-bs

 arch/arm64/mm/pageattr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 5135f2d66958..08ac96b9f846 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -148,7 +148,6 @@ static int change_memory_common(unsigned long addr, int numpages,
 	unsigned long size = PAGE_SIZE * numpages;
 	unsigned long end = start + size;
 	struct vm_struct *area;
-	int i;
 
 	if (!PAGE_ALIGNED(addr)) {
 		start &= PAGE_MASK;
@@ -184,8 +183,9 @@ static int change_memory_common(unsigned long addr, int numpages,
 	 */
 	if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
 			    pgprot_val(clear_mask) == PTE_RDONLY)) {
-		for (i = 0; i < area->nr_pages; i++) {
-			__change_memory_common((u64)page_address(area->pages[i]),
+		unsigned long idx = (start - (unsigned long)area->addr) >> PAGE_SHIFT;
+		for (; numpages; idx++, numpages--) {
+			__change_memory_common((u64)page_address(area->pages[idx]),
 					       PAGE_SIZE, set_mask, clear_mask);
 		}
 	}
-- 
2.47.0