linux-kernel - [PATCH] arm64: kprobes: check the return value of set_memory

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Message-ID: <20251103194505.4077265-1-yang@os.amperecomputing.com>
Date: Mon,  3 Nov 2025 11:45:05 -0800
From: Yang Shi <yang@...amperecomputing.com>
To: catalin.marinas@....com,
	will@...nel.org,
	ryan.roberts@....com
Cc: yang@...amperecomputing.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] arm64: kprobes: check the return value of set_memory_rox()

Since commit a166563e7ec3 ("arm64: mm: support large block mapping when
rodata=full"), __change_memory_common has more chance to fail due to
memory allocation fialure when splitting page table. So check the return
value of set_memory_rox(), then bail out if it fails otherwise we may have
RW memory mapping for kprobes insn page.

Fixes: 195a1b7d8388 ("arm64: kprobes: call set_memory_rox() for kprobe page")
Signed-off-by: Yang Shi <yang@...amperecomputing.com>
---
I actually epxected 195a1b7d8388 ("arm64: kprobes: call set_memory_rox()
for kprobe page") can be merged in 6.17-rcX, so I just restored it to
before commit 10d5e97c1bf8 ("arm64: use PAGE_KERNEL_ROX directly in
alloc_insn_page"), however it turned out to be merged in 6.18-rc1 and it
is after commit a166563e7ec3 ("arm64: mm: support large block mapping when
rodata=full"). So I made the fix tag point to it.
And I don't think we need to backport this patch to pre-6.18.

 arch/arm64/kernel/probes/kprobes.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index 8ab6104a4883..43a0361a8bf0 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -49,7 +49,10 @@ void *alloc_insn_page(void)
 	addr = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
 	if (!addr)
 		return NULL;
-	set_memory_rox((unsigned long)addr, 1);
+	if (set_memory_rox((unsigned long)addr, 1)) {
+		execmem_free(addr);
+		return NULL;
+	}
 	return addr;
 }
 
-- 
2.47.0