Re: [PATCH] mm: /proc/pid/smaps_rollup: fix no vma's null-deref

On Mon, 3 Oct 2022 18:45:31 -0400 FirstName LastName sethjenkins@google.com wrote:

From: Seth Jenkins sethjenkins@google.com

Commit 258f669e7e88 ("mm: /proc/pid/smaps_rollup: convert to single value seq_file") introduced a null-deref if there are no vma's in the task in show_smaps_rollup.

--- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -969,7 +969,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v) vma = vma->vm_next; }

• show_vma_header_prefix(m, priv->mm->mmap->vm_start,

• show_vma_header_prefix(m, priv->mm->mmap ? priv->mm->mmap->vm_start : 0, last_vma_end, 0, 0, 0, 0); seq_pad(m, ' '); seq_puts(m, "[rollup]\n");

The current mm tree is very different here. In fact the bug might not exist any more. Please take a look at the mm-stable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm?

If no fixes are needed in mm-stable then I guess the process is to propose this patch to the stable tree maintainers.