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FAILED: patch "[PATCH] mm: refactor map_deny_write_exec()" failed to apply to 6.11-stable tree

PATCH [email protected] 1 participant 1 message Nov 11, 2024

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The patch below does not apply to the 6.11-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.11.y
git checkout FETCH_HEAD
git cherry-pick -x 0fb4a7ad270b3b209e510eb9dc5b07bf02b7edaf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024111109-deck-cranial-851e@gregkh' --subject-prefix 'PATCH 6.11.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0fb4a7ad270b3b209e510eb9dc5b07bf02b7edaf Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <[email protected]>
Date: Tue, 29 Oct 2024 18:11:46 +0000
Subject: [PATCH] mm: refactor map_deny_write_exec()

Refactor the map_deny_write_exec() to not unnecessarily require a VMA parameter but rather to accept VMA flags parameters, which allows us to use this function early in mmap_region() in a subsequent commit.

While we're here, we refactor the function to be more readable and add some additional documentation.

Link https://lkml.kernel.org/r/6be8bb59cd7c68006ebb006eb9d8dc27104b1f70.1730224667.git.lorenzo.stoakes@oracle.com open here
Fixes deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by Lorenzo Stoakes <[email protected]>
Reported-by Jann Horn <[email protected]>
Reviewed-by Liam R. Howlett <[email protected]>
Reviewed-by Vlastimil Babka <[email protected]>
Reviewed-by Jann Horn <[email protected]>
Cc Andreas Larsson <[email protected]>
Cc Catalin Marinas <[email protected]>
Cc David S. Miller <[email protected]>
Cc Helge Deller <[email protected]>
Cc James E.J. Bottomley <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Mark Brown <[email protected]>
Cc Peter Xu <[email protected]>
Cc Will Deacon <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
include/linux/mman.h +18 -3
index bcb201ab7a41..8ddca62d6460 100644
@@ -188,16 +188,31 @@ static inline bool arch_memory_deny_write_exec_supported(void)
  *
  *	d)	mmap(PROT_READ | PROT_EXEC)
  *		mmap(PROT_READ | PROT_EXEC | PROT_BTI)
+ *
+ * This is only applicable if the user has set the Memory-Deny-Write-Execute
+ * (MDWE) protection mask for the current process.
+ *
+ * @old specifies the VMA flags the VMA originally possessed, and @new the ones
+ * we propose to set.
+ *
+ * Return: false if proposed change is OK, true if not ok and should be denied.
  */
-static inline bool map_deny_write_exec(struct vm_area_struct *vma,  unsigned long vm_flags)
+static inline bool map_deny_write_exec(unsigned long old, unsigned long new)
 {
+	/* If MDWE is disabled, we have nothing to deny. */
 	if (!test_bit(MMF_HAS_MDWE, &current->mm->flags))
 		return false;
 
-	if ((vm_flags & VM_EXEC) && (vm_flags & VM_WRITE))
+	/* If the new VMA is not executable, we have nothing to deny. */
+	if (!(new & VM_EXEC))
+		return false;
+
+	/* Under MDWE we do not accept newly writably executable VMAs... */
+	if (new & VM_WRITE)
 		return true;
 
-	if (!(vma->vm_flags & VM_EXEC) && (vm_flags & VM_EXEC))
+	/* ...nor previously non-executable VMAs becoming executable. */
+	if (!(old & VM_EXEC))
 		return true;
 
 	return false;
mm/mmap.c +1 -1
index ac0604f146f6..ab71d4c3464c 100644
@@ -1505,7 +1505,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		vma_set_anonymous(vma);
 	}
 
-	if (map_deny_write_exec(vma, vma->vm_flags)) {
+	if (map_deny_write_exec(vma->vm_flags, vma->vm_flags)) {
 		error = -EACCES;
 		goto close_and_free_vma;
 	}
mm/mprotect.c +1 -1
index 0c5d6d06107d..6f450af3252e 100644
@@ -810,7 +810,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 			break;
 		}
 
-		if (map_deny_write_exec(vma, newflags)) {
+		if (map_deny_write_exec(vma->vm_flags, newflags)) {
 			error = -EACCES;
 			break;
 		}
mm/vma.h +1 -1
index 75558b5e9c8c..d58068c0ff2e 100644
@@ -42,7 +42,7 @@ struct vma_munmap_struct {
 	int vma_count;                  /* Number of vmas that will be removed */
 	bool unlock;                    /* Unlock after the munmap */
 	bool clear_ptes;                /* If there are outstanding PTE to be cleared */
-	/* 1 byte hole */
+	/* 2 byte hole */
 	unsigned long nr_pages;         /* Number of pages being removed */
 	unsigned long locked_vm;        /* Number of locked pages */
 	unsigned long nr_accounted;     /* Number of VM_ACCOUNT pages */