| Message ID | 20221003224531.1930646-1-sethjenkins@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: /proc/pid/smaps_rollup: fix no vma's null-deref | expand |
On Mon, Oct 03, 2022 at 06:45:31PM -0400, FirstName LastName 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. > > 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> > --- 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"); Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Tested-by: Alexey Dobriyan <adobriyan@gmail.com> Now I know how to create stable process without address space.
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.
I concur, mm-stable looks fine to me as well. Jann and I conversed today and the tentative decision since this isn't considered a high-priority security bug is to wait for maple tree to merge into Linus's branch before submitting this patch to stable. On Tue, Oct 4, 2022 at 2:46 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > 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. >
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 4e0023643f8b..1e7bbc0873a4 100644 --- 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");