linux-kernel - [PATCH] um: Don't mark stack executable

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Message-ID: <20250726122930.236404-1-richard@nod.at>
Date: Sat, 26 Jul 2025 14:29:30 +0200
From: Richard Weinberger <richard@....at>
To: linux-um@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	richard@....at,
	anton.ivanov@...bridgegreys.com,
	johannes@...solutions.net,
	benjamin.berg@...el.com
Subject: [PATCH] um: Don't mark stack executable

On one of my machines UML failed to start after enabling
SELinux.
UML failed to start because SELinux's execmod rule denies
executable pages on a modified file mapping.

Historically UML marks it's stack rwx.
AFAICT, these days this is no longer needed, so let's remove
PROT_EXEC.

Signed-off-by: Richard Weinberger <richard@....at>
---
 arch/um/os-Linux/util.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 4193e04d7e4a7..e3ad71a0d13c4 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -20,8 +20,7 @@
 
 void stack_protections(unsigned long address)
 {
-	if (mprotect((void *) address, UM_THREAD_SIZE,
-		    PROT_READ | PROT_WRITE | PROT_EXEC) < 0)
+	if (mprotect((void *) address, UM_THREAD_SIZE, PROT_READ | PROT_WRITE) < 0)
 		panic("protecting stack failed, errno = %d", errno);
 }
 
-- 
2.49.0