kernel 6.9.12 selinux vma revert

1 files changed, 57 insertions, 0 deletions

diff --git a/SOURCES/0001-selinux-revert-our-use-of-vma_is_initial_heap.patch b/SOURCES/0001-selinux-revert-our-use-of-vma_is_initial_heap.patch
new file mode 100644
index 0000000..da1afef
--- /dev/null
+++ b/SOURCES/0001-selinux-revert-our-use-of-vma_is_initial_heap.patch
@@ -0,0 +1,57 @@
+From 05a3d6e9307250a5911d75308e4363466794ab21 Mon Sep 17 00:00:00 2001
+From: Paul Moore <paul@paul-moore.com>
+Date: Thu, 8 Aug 2024 11:57:38 -0400
+Subject: [PATCH] selinux: revert our use of vma_is_initial_heap()
+
+Unfortunately it appears that vma_is_initial_heap() is currently broken
+for applications that do not currently have any heap allocated, e.g.
+brk == start_brk.  The breakage is such that it will cause SELinux to
+check for the process/execheap permission on memory regions that cross
+brk/start_brk even when there is no heap.
+
+The proper fix would be to correct vma_is_initial_heap(), but as there
+are multiple callers I am hesitant to unilaterally modify the helper
+out of concern that I would end up breaking some other subsystem.  The
+mm developers have been made aware of the situation and hopefully they
+will have a fix at some point in the future, but we need a fix soon so
+we are simply going to revert our use of vma_is_initial_heap() in favor
+of our old logic/code which works as expected, even in the face of a
+zero size heap.  We can return to using vma_is_initial_heap() at some
+point in the future when it is fixed.
+
+Cc: stable@vger.kernel.org
+Reported-by: Marc Reisner <reisner.marc@gmail.com>
+Closes: https://lore.kernel.org/all/ZrPmoLKJEf1wiFmM@marcreisner.com
+Fixes: 68df1baf158f ("selinux: use vma_is_initial_stack() and vma_is_initial_heap()")
+Signed-off-by: Paul Moore <paul@paul-moore.com>
+Signed-off-by: Jan200101 <sentrycraft123@gmail.com>
+---
+ security/selinux/hooks.c | 12 +++++++++++-
+ 1 file changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
+index 55c78c318ccd..bfa61e005aac 100644
+--- a/security/selinux/hooks.c
++++ b/security/selinux/hooks.c
+@@ -3852,7 +3852,17 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
+ 	if (default_noexec &&
+ 	    (prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) {
+ 		int rc = 0;
+-		if (vma_is_initial_heap(vma)) {
++		/*
++		 * We don't use the vma_is_initial_heap() helper as it has
++		 * a history of problems and is currently broken on systems
++		 * where there is no heap, e.g. brk == start_brk.  Before
++		 * replacing the conditional below with vma_is_initial_heap(),
++		 * or something similar, please ensure that the logic is the
++		 * same as what we have below or you have tested every possible
++		 * corner case you can think to test.
++		 */
++		if (vma->vm_start >= vma->vm_mm->start_brk &&
++		    vma->vm_end <= vma->vm_mm->brk) {
+ 			rc = avc_has_perm(sid, sid, SECCLASS_PROCESS,
+ 					  PROCESS__EXECHEAP, NULL);
+ 		} else if (!vma->vm_file && (vma_is_initial_stack(vma) ||
+-- 
+2.46.0
+