From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1AE5C1A682C for ; Wed, 29 Apr 2026 04:00:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777435231; cv=none; b=BE758KdN3S/6YUZ3HUGZCL9foeWpU5odSvWEi+Gsycr8l7tQR+6C2grPjaSAMlLOOOubA04OScpN9V7YqJGzvA8ooF3UMhruAAVvaZH81+Dbt3yfrUZxbzfaPWTkaFsAR1+Yd21gfG/n6jPn0Cx7jvkxrKnKifhz5nUHJJN0X74= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777435231; c=relaxed/simple; bh=Vuxb4Z+qd6r7e+UhEv2ZRsLXmdLEkl5/lprIyIu1Szk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rRHuX0GCaTIV1cPRoIOtGsXzdmpBbxL1pZfYfwC6EH2OvNrQhTi8bTIyYRZqEFeAZmdTkHRdV3sif35fqnWx/1GVSIvLRXVwuA8cm12IKovTcMCpMsBHrYKIJoAfMYyuWMDwrBcW6np5v28EFtQSisSwfahKb3EhPRdBQZ/WCQo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fZ7EH/tB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fZ7EH/tB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26996C19425; Wed, 29 Apr 2026 04:00:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777435230; bh=Vuxb4Z+qd6r7e+UhEv2ZRsLXmdLEkl5/lprIyIu1Szk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fZ7EH/tB6/+N6LjRKn+ykSN4ihp+JaUwTsUwuNb9Lq2mR6Dx4A3BU6tGUyW6bL/px yvgLAocUQfql9RBfG/WMg8yPW3BS2p+qgqrzmwHTwT1FZCFF47QQmiYcu71EeYuxZ5 +RHFYRbOV5qnKJD7hSc2ltm+dK8cgvue42133NLRFAOjOdMPb+zzip4O/uDUERfM8m YESjk07KhPlvoidwVAJzC5cjMZBl8KZsJ1uhJuL1GK4Wq1WJK8szRTmcMhapgd8txe bZ7IUmpPgLfRvRod0Tvtsniz3pTVn5pRmT45oYTp9dxV6mBXsUZJ6sg4LDqkcahs+j 8+zGXDKde8Uvw== From: Sasha Levin To: stable@vger.kernel.org Cc: Anthony Yznaga , David Hildenbrand , Pedro Falcato , "Lorenzo Stoakes (Oracle)" , Jann Horn , "Jason A. Donenfeld" , Liam Howlett , Michal Hocko , Mike Rapoport , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , Andrew Morton , Sasha Levin Subject: [PATCH 6.12.y] mm: prevent droppable mappings from being locked Date: Wed, 29 Apr 2026 00:00:27 -0400 Message-ID: <20260429040027.3341979-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026042736-vascular-rubbed-001c@gregkh> References: <2026042736-vascular-rubbed-001c@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Anthony Yznaga [ Upstream commit d239462787b072c78eb19fc1f155c3d411256282 ] Droppable mappings must not be lockable. There is a check for VMAs with VM_DROPPABLE set in mlock_fixup() along with checks for other types of unlockable VMAs which ensures this when calling mlock()/mlock2(). For mlockall(MCL_FUTURE), the check for unlockable VMAs is different. In apply_mlockall_flags(), if the flags parameter has MCL_FUTURE set, the current task's mm's default VMA flag field mm->def_flags has VM_LOCKED applied to it. VM_LOCKONFAULT is also applied if MCL_ONFAULT is also set. When these flags are set as default in this manner they are cleared in __mmap_complete() for new mappings that do not support mlock. A check for VM_DROPPABLE in __mmap_complete() is missing resulting in droppable mappings created with VM_LOCKED set. To fix this and reduce that chance of similar bugs in the future, introduce and use vma_supports_mlock(). Link: https://lkml.kernel.org/r/20260310155821.17869-1-anthony.yznaga@oracle.com Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Signed-off-by: Anthony Yznaga Suggested-by: David Hildenbrand Acked-by: David Hildenbrand (Arm) Reviewed-by: Pedro Falcato Reviewed-by: Lorenzo Stoakes (Oracle) Tested-by: Lorenzo Stoakes (Oracle) Cc: Jann Horn Cc: Jason A. Donenfeld Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton [ adapted change to `mm/mmap.c::__mmap_region()` instead of `mm/vma.c::__mmap_complete()` ] Signed-off-by: Sasha Levin --- include/linux/hugetlb_inline.h | 4 ++-- mm/internal.h | 10 ++++++++++ mm/mlock.c | 10 ++++++---- mm/mmap.c | 4 +--- 4 files changed, 19 insertions(+), 9 deletions(-) diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h index 0660a03d37d98..846185ea626c7 100644 --- a/include/linux/hugetlb_inline.h +++ b/include/linux/hugetlb_inline.h @@ -6,14 +6,14 @@ #include -static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma) +static inline bool is_vm_hugetlb_page(const struct vm_area_struct *vma) { return !!(vma->vm_flags & VM_HUGETLB); } #else -static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma) +static inline bool is_vm_hugetlb_page(const struct vm_area_struct *vma) { return false; } diff --git a/mm/internal.h b/mm/internal.h index b7b942767c702..3bfc1dc2d7eaf 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1015,6 +1015,16 @@ static inline struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf, } return fpin; } + +static inline bool vma_supports_mlock(const struct vm_area_struct *vma) +{ + if (vma->vm_flags & (VM_SPECIAL | VM_DROPPABLE)) + return false; + if (vma_is_dax(vma) || is_vm_hugetlb_page(vma)) + return false; + return vma != get_gate_vma(current->mm); +} + #else /* !CONFIG_MMU */ static inline void unmap_mapping_folio(struct folio *folio) { } static inline void mlock_new_folio(struct folio *folio) { } diff --git a/mm/mlock.c b/mm/mlock.c index 8c8d522efdd59..d16bf4dbd06dd 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -472,10 +472,12 @@ static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma, int ret = 0; vm_flags_t oldflags = vma->vm_flags; - if (newflags == oldflags || (oldflags & VM_SPECIAL) || - is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) || - vma_is_dax(vma) || vma_is_secretmem(vma) || (oldflags & VM_DROPPABLE)) - /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */ + if (newflags == oldflags || vma_is_secretmem(vma) || + !vma_supports_mlock(vma)) + /* + * Don't set VM_LOCKED or VM_LOCKONFAULT and don't count. + * For secretmem, don't allow the memory to be unlocked. + */ goto out; vma = vma_modify_flags(vmi, *prev, vma, start, end, newflags); diff --git a/mm/mmap.c b/mm/mmap.c index 6183805f6f9e6..d361b1058da10 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1547,9 +1547,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, vm_stat_account(mm, vm_flags, pglen); if (vm_flags & VM_LOCKED) { - if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || - is_vm_hugetlb_page(vma) || - vma == get_gate_vma(current->mm)) + if (!vma_supports_mlock(vma)) vm_flags_clear(vma, VM_LOCKED_MASK); else mm->locked_vm += pglen; -- 2.53.0