From: Seth Jenkins <sethjenkins@google.com>

Date: Mon,  3 Oct 2022 18:45:31 -0400

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

Patch-mainline: Never, fixed differently

References: bsc#1207769

mhocko@suse.com:

The upstream has fixed by c4c84f06285e ("fs/proc/task_mmu: stop using linked

list and highest_vm_end") which is a larger chabge not really suitable for

backporintg.

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.

Fixes: 258f669e7e88 ("mm: /proc/pid/smaps_rollup: convert to single value seq_file")

Cc: stable@vger.kernel.org

Signed-off-by: Seth Jenkins <sethjenkins@google.com>

Acked-by: Michal Hocko <mhocko@suse.com>

---

 fs/proc/task_mmu.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/proc/task_mmu.c

+++ b/fs/proc/task_mmu.c

@@ -876,7 +876,7 @@ static int show_smaps_rollup(struct seq_

 		last_vma_end = vma->vm_end;

 	}

-	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");