From: Seth Jenkins <sethjenkins@google.com>
Date: Thu, 27 Oct 2022 15:36:52 +0000 (-0400)
Subject: mm: /proc/pid/smaps_rollup: fix no vma's null-deref
X-Git-Tag: v5.10.152~2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a50ed2d28727ff605d95fb9a53be8ff94e8eaaf4;p=users%2Fdwmw2%2Flinux.git

mm: /proc/pid/smaps_rollup: fix no vma's null-deref

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")
Signed-off-by: Seth Jenkins <sethjenkins@google.com>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Tested-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index ef18f0d71b11b..8b75a04836b63 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -951,7 +951,7 @@ 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");