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 EFA771C27; Fri, 6 Jun 2025 04:56:11 +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=1749185772; cv=none; b=qxyDql6dH1D7cFA5KWXC5fKHgssLrZiQK8s+9MSmXf6g7e88a+kvnPVfHTp2n37CIcgjuDQtuOD6X7GbwKgJpVk39ST+AdKW+dWjyF3mX6XG85wovDlMSMesGGf/LNM06fnKmtdJZOZzLUfRqj8UKLO2UjvnRmLa0zd5Wo8U1PI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749185772; c=relaxed/simple; bh=i3SIkCrWanC8LMSdAYfDWqW3FVKIi9IIfUm/rBNmtLU=; h=Date:To:From:Subject:Message-Id; b=LrxKKFOs0ZjVATeLDDkD9cyvE1UXQHMEJHmp/gSo+5cya59X0HcSDHE00LuB8nolbLsgrhrUCJXMGBSGzGd0wkiwL63l5McqDfdJV3vHk05esVuWMa2jweAmJGPF6K0ZKaRbn5HOs5g/tuWHTzaWiveLOCqkwuxPPQ7Eh3MB634= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=ArCGLAe+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="ArCGLAe+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52FA4C4CEEB; Fri, 6 Jun 2025 04:56:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1749185771; bh=i3SIkCrWanC8LMSdAYfDWqW3FVKIi9IIfUm/rBNmtLU=; h=Date:To:From:Subject:From; b=ArCGLAe+h54X+JasqHjsRpc93bY15KdKUryfz8vc4owM9RvIaI4LwZU7rM92s8fAO zG59iXhRcz2vu99gnzPVN/4THIN5pN4oetaYZyJG+PJIf5vTYuDdDNDsw6UWlV8gfp 69v9XA3iQBqWghM3s2BTG65/0JPyk+e6q9aV5zLA= Date: Thu, 05 Jun 2025 21:56:10 -0700 To: mm-commits@vger.kernel.org,vbabka@suse.cz,stable@vger.kernel.org,peterz@infradead.org,oleg@redhat.com,mhiramat@kernel.org,lorenzo.stoakes@oracle.com,liam.howlett@oracle.com,jannh@google.com,david@redhat.com,pulehui@huawei.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-fix-uprobe-pte-be-overwritten-when-expanding-vma.patch removed from -mm tree Message-Id: <20250606045611.52FA4C4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: fix uprobe pte be overwritten when expanding vma has been removed from the -mm tree. Its filename was mm-fix-uprobe-pte-be-overwritten-when-expanding-vma.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pu Lehui Subject: mm: fix uprobe pte be overwritten when expanding vma Date: Thu, 29 May 2025 15:56:47 +0000 Patch series "Fix uprobe pte be overwritten when expanding vma". This patch (of 4): We encountered a BUG alert triggered by Syzkaller as follows: BUG: Bad rss-counter state mm:00000000b4a60fca type:MM_ANONPAGES val:1 And we can reproduce it with the following steps: 1. register uprobe on file at zero offset 2. mmap the file at zero offset: addr1 = mmap(NULL, 2 * 4096, PROT_NONE, MAP_PRIVATE, fd, 0); 3. mremap part of vma1 to new vma2: addr2 = mremap(addr1, 4096, 2 * 4096, MREMAP_MAYMOVE); 4. mremap back to orig addr1: mremap(addr2, 4096, 4096, MREMAP_MAYMOVE | MREMAP_FIXED, addr1); In step 3, the vma1 range [addr1, addr1 + 4096] will be remap to new vma2 with range [addr2, addr2 + 8192], and remap uprobe anon page from the vma1 to vma2, then unmap the vma1 range [addr1, addr1 + 4096]. In step 4, the vma2 range [addr2, addr2 + 4096] will be remap back to the addr range [addr1, addr1 + 4096]. Since the addr range [addr1 + 4096, addr1 + 8192] still maps the file, it will take vma_merge_new_range to expand the range, and then do uprobe_mmap in vma_complete. Since the merged vma pgoff is also zero offset, it will install uprobe anon page to the merged vma. However, the upcomming move_page_tables step, which use set_pte_at to remap the vma2 uprobe pte to the merged vma, will overwrite the newly uprobe pte in the merged vma, and lead that pte to be orphan. Since the uprobe pte will be remapped to the merged vma, we can remove the unnecessary uprobe_mmap upon merged vma. This problem was first found in linux-6.6.y and also exists in the community syzkaller: https://lore.kernel.org/all/000000000000ada39605a5e71711@google.com/T/ Link: https://lkml.kernel.org/r/20250529155650.4017699-1-pulehui@huaweicloud.com Link: https://lkml.kernel.org/r/20250529155650.4017699-2-pulehui@huaweicloud.com Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Signed-off-by: Pu Lehui Suggested-by: Lorenzo Stoakes Reviewed-by: Lorenzo Stoakes Acked-by: David Hildenbrand Cc: Jann Horn Cc: Liam Howlett Cc: "Masami Hiramatsu (Google)" Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/vma.c | 20 +++++++++++++++++--- mm/vma.h | 7 +++++++ 2 files changed, 24 insertions(+), 3 deletions(-) --- a/mm/vma.c~mm-fix-uprobe-pte-be-overwritten-when-expanding-vma +++ a/mm/vma.c @@ -169,6 +169,9 @@ static void init_multi_vma_prep(struct v vp->file = vma->vm_file; if (vp->file) vp->mapping = vma->vm_file->f_mapping; + + if (vmg && vmg->skip_vma_uprobe) + vp->skip_vma_uprobe = true; } /* @@ -358,10 +361,13 @@ static void vma_complete(struct vma_prep if (vp->file) { i_mmap_unlock_write(vp->mapping); - uprobe_mmap(vp->vma); - if (vp->adj_next) - uprobe_mmap(vp->adj_next); + if (!vp->skip_vma_uprobe) { + uprobe_mmap(vp->vma); + + if (vp->adj_next) + uprobe_mmap(vp->adj_next); + } } if (vp->remove) { @@ -1823,6 +1829,14 @@ struct vm_area_struct *copy_vma(struct v faulted_in_anon_vma = false; } + /* + * If the VMA we are copying might contain a uprobe PTE, ensure + * that we do not establish one upon merge. Otherwise, when mremap() + * moves page tables, it will orphan the newly created PTE. + */ + if (vma->vm_file) + vmg.skip_vma_uprobe = true; + new_vma = find_vma_prev(mm, addr, &vmg.prev); if (new_vma && new_vma->vm_start < addr + len) return NULL; /* should never get here */ --- a/mm/vma.h~mm-fix-uprobe-pte-be-overwritten-when-expanding-vma +++ a/mm/vma.h @@ -19,6 +19,8 @@ struct vma_prepare { struct vm_area_struct *insert; struct vm_area_struct *remove; struct vm_area_struct *remove2; + + bool skip_vma_uprobe :1; }; struct unlink_vma_file_batch { @@ -120,6 +122,11 @@ struct vma_merge_struct { */ bool give_up_on_oom :1; + /* + * If set, skip uprobe_mmap upon merged vma. + */ + bool skip_vma_uprobe :1; + /* Internal flags set during merge process: */ /* _ Patches currently in -mm which might be from pulehui@huawei.com are