The patch below does not apply to the 5.15-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 stable@vger.kernel.org.

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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 0fb4a7ad270b3b209e510eb9dc5b07bf02b7edaf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024111112-headless-facelift-4a02@gregkh' --subject-prefix 'PATCH 5.15.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 lorenzo.stoakes@oracle.com 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/6be8bb59cd7c68006ebb006eb9d8dc27104b1f70.173022466... Fixes: deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails") Signed-off-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reported-by: Jann Horn jannh@google.com Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Reviewed-by: Vlastimil Babka vbabka@suse.cz Reviewed-by: Jann Horn jannh@google.com Cc: Andreas Larsson andreas@gaisler.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: David S. Miller davem@davemloft.net Cc: Helge Deller deller@gmx.de Cc: James E.J. Bottomley James.Bottomley@HansenPartnership.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Mark Brown broonie@kernel.org Cc: Peter Xu peterx@redhat.com Cc: Will Deacon will@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/include/linux/mman.h b/include/linux/mman.h index bcb201ab7a41..8ddca62d6460 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -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; diff --git a/mm/mmap.c b/mm/mmap.c index ac0604f146f6..ab71d4c3464c 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -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; } diff --git a/mm/mprotect.c b/mm/mprotect.c index 0c5d6d06107d..6f450af3252e 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -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; } diff --git a/mm/vma.h b/mm/vma.h index 75558b5e9c8c..d58068c0ff2e 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -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 */