Re: [PATCH] binder: make sure fd closes complete

2021-09-14 Thread Greg KH
On Fri, Sep 03, 2021 at 12:38:26PM -0700, Todd Kjos wrote:
> On Fri, Sep 3, 2021 at 1:06 AM Dan Carpenter  wrote:
> >
> > On Thu, Sep 02, 2021 at 08:35:35AM -0700, Todd Kjos wrote:
> > > On Tue, Aug 31, 2021 at 12:24 AM Martijn Coenen  wrote:
> > > >
> > > > On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team
> > > >  wrote:
> > > > >
> > > > > During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> > > > > cleanup may close 1 or more fds. The close operations are
> > > > > completed using the task work mechanism -- which means the thread
> > > > > needs to return to userspace or the file object may never be
> > > > > dereferenced -- which can lead to hung processes.
> > > > >
> > > > > Force the binder thread back to userspace if an fd is closed during
> > > > > BC_FREE_BUFFER handling.
> > > > >
> > > > > Signed-off-by: Todd Kjos 
> > > > Reviewed-by: Martijn Coenen 
> > >
> > > Please also add to stable releases 5.4 and later.
> >
> > It would be better if this had a fixes tag so we knew which is the first
> > buggy commit.
> >
> > There was a long Project Zero article about the Bad Binder exploit
> > because commit f5cb779ba163 ("ANDROID: binder: remove waitqueue when
> > thread exits.") was marked as # 4.14 but it didn't have a Fixes tag and
> > the actual buggy commit was in 4.9.
> 
> Good point Dan. I should have included a Fixes tag. Here is the tag
> (issue introduced in 4.20):
> 
> Fixes: 80cd795630d6 ("binder: fix use-after-free due to ksys_close()
> during fdget()")
> 
> Greg- would you like me to send a v2 with the Fixes tag and CC'ing
> stable appropriately?

I've added it to the commit when I added it to my tree, no need to
resend.

thanks,

greg k-h
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Re: [PATCH] binder: make sure fd closes complete

2021-09-03 Thread Todd Kjos
On Fri, Sep 3, 2021 at 1:06 AM Dan Carpenter  wrote:
>
> On Thu, Sep 02, 2021 at 08:35:35AM -0700, Todd Kjos wrote:
> > On Tue, Aug 31, 2021 at 12:24 AM Martijn Coenen  wrote:
> > >
> > > On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team
> > >  wrote:
> > > >
> > > > During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> > > > cleanup may close 1 or more fds. The close operations are
> > > > completed using the task work mechanism -- which means the thread
> > > > needs to return to userspace or the file object may never be
> > > > dereferenced -- which can lead to hung processes.
> > > >
> > > > Force the binder thread back to userspace if an fd is closed during
> > > > BC_FREE_BUFFER handling.
> > > >
> > > > Signed-off-by: Todd Kjos 
> > > Reviewed-by: Martijn Coenen 
> >
> > Please also add to stable releases 5.4 and later.
>
> It would be better if this had a fixes tag so we knew which is the first
> buggy commit.
>
> There was a long Project Zero article about the Bad Binder exploit
> because commit f5cb779ba163 ("ANDROID: binder: remove waitqueue when
> thread exits.") was marked as # 4.14 but it didn't have a Fixes tag and
> the actual buggy commit was in 4.9.

Good point Dan. I should have included a Fixes tag. Here is the tag
(issue introduced in 4.20):

Fixes: 80cd795630d6 ("binder: fix use-after-free due to ksys_close()
during fdget()")

Greg- would you like me to send a v2 with the Fixes tag and CC'ing
stable appropriately?

>
> regards,
> dan carpenter
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to kernel-team+unsubscr...@android.com.
>
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Re: [PATCH] binder: make sure fd closes complete

2021-09-03 Thread Dan Carpenter
On Thu, Sep 02, 2021 at 08:35:35AM -0700, Todd Kjos wrote:
> On Tue, Aug 31, 2021 at 12:24 AM Martijn Coenen  wrote:
> >
> > On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team
> >  wrote:
> > >
> > > During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> > > cleanup may close 1 or more fds. The close operations are
> > > completed using the task work mechanism -- which means the thread
> > > needs to return to userspace or the file object may never be
> > > dereferenced -- which can lead to hung processes.
> > >
> > > Force the binder thread back to userspace if an fd is closed during
> > > BC_FREE_BUFFER handling.
> > >
> > > Signed-off-by: Todd Kjos 
> > Reviewed-by: Martijn Coenen 
> 
> Please also add to stable releases 5.4 and later.

It would be better if this had a fixes tag so we knew which is the first
buggy commit.

There was a long Project Zero article about the Bad Binder exploit
because commit f5cb779ba163 ("ANDROID: binder: remove waitqueue when
thread exits.") was marked as # 4.14 but it didn't have a Fixes tag and
the actual buggy commit was in 4.9.

regards,
dan carpenter
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Re: [PATCH] binder: make sure fd closes complete

2021-09-02 Thread Greg KH
On Thu, Sep 02, 2021 at 08:35:35AM -0700, Todd Kjos wrote:
> On Tue, Aug 31, 2021 at 12:24 AM Martijn Coenen  wrote:
> >
> > On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team
> >  wrote:
> > >
> > > During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> > > cleanup may close 1 or more fds. The close operations are
> > > completed using the task work mechanism -- which means the thread
> > > needs to return to userspace or the file object may never be
> > > dereferenced -- which can lead to hung processes.
> > >
> > > Force the binder thread back to userspace if an fd is closed during
> > > BC_FREE_BUFFER handling.
> > >
> > > Signed-off-by: Todd Kjos 
> > Reviewed-by: Martijn Coenen 
> 
> Please also add to stable releases 5.4 and later.

I'll try to remember to tag this as-such after 5.15-rc1 is out and I can
apply it to my tree.  But in the future, it's best if you add the cc:
stable to the patch yourself so I don't have to do it "by hand" after
the fact.

thanks,

greg k-h
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Re: [PATCH] binder: make sure fd closes complete

2021-08-31 Thread Martijn Coenen
On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team
 wrote:
>
> During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> cleanup may close 1 or more fds. The close operations are
> completed using the task work mechanism -- which means the thread
> needs to return to userspace or the file object may never be
> dereferenced -- which can lead to hung processes.
>
> Force the binder thread back to userspace if an fd is closed during
> BC_FREE_BUFFER handling.
>
> Signed-off-by: Todd Kjos 
Reviewed-by: Martijn Coenen 

> ---
>  drivers/android/binder.c | 23 +--
>  1 file changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index bcec598b89f2..c2823f0d588f 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -1852,6 +1852,7 @@ static void binder_deferred_fd_close(int fd)
>  }
>
>  static void binder_transaction_buffer_release(struct binder_proc *proc,
> + struct binder_thread *thread,
>   struct binder_buffer *buffer,
>   binder_size_t failed_at,
>   bool is_failure)
> @@ -2011,8 +2012,16 @@ static void binder_transaction_buffer_release(struct 
> binder_proc *proc,
> >alloc, , buffer,
> offset, sizeof(fd));
> WARN_ON(err);
> -   if (!err)
> +   if (!err) {
> binder_deferred_fd_close(fd);
> +   /*
> +* Need to make sure the thread goes
> +* back to userspace to complete the
> +* deferred close
> +*/
> +   if (thread)
> +   thread->looper_need_return = 
> true;
> +   }
> }
> } break;
> default:
> @@ -3105,7 +3114,7 @@ static void binder_transaction(struct binder_proc *proc,
>  err_copy_data_failed:
> binder_free_txn_fixups(t);
> trace_binder_transaction_failed_buffer_release(t->buffer);
> -   binder_transaction_buffer_release(target_proc, t->buffer,
> +   binder_transaction_buffer_release(target_proc, NULL, t->buffer,
>   buffer_offset, true);
> if (target_node)
> binder_dec_node_tmpref(target_node);
> @@ -3184,7 +3193,9 @@ static void binder_transaction(struct binder_proc *proc,
>   * Cleanup buffer and free it.
>   */
>  static void
> -binder_free_buf(struct binder_proc *proc, struct binder_buffer *buffer)
> +binder_free_buf(struct binder_proc *proc,
> +   struct binder_thread *thread,
> +   struct binder_buffer *buffer)
>  {
> binder_inner_proc_lock(proc);
> if (buffer->transaction) {
> @@ -3212,7 +3223,7 @@ binder_free_buf(struct binder_proc *proc, struct 
> binder_buffer *buffer)
> binder_node_inner_unlock(buf_node);
> }
> trace_binder_transaction_buffer_release(buffer);
> -   binder_transaction_buffer_release(proc, buffer, 0, false);
> +   binder_transaction_buffer_release(proc, thread, buffer, 0, false);
> binder_alloc_free_buf(>alloc, buffer);
>  }
>
> @@ -3414,7 +3425,7 @@ static int binder_thread_write(struct binder_proc *proc,
>  proc->pid, thread->pid, (u64)data_ptr,
>  buffer->debug_id,
>  buffer->transaction ? "active" : 
> "finished");
> -   binder_free_buf(proc, buffer);
> +   binder_free_buf(proc, thread, buffer);
> break;
> }
>
> @@ -4107,7 +4118,7 @@ static int binder_thread_read(struct binder_proc *proc,
> buffer->transaction = NULL;
> binder_cleanup_transaction(t, "fd fixups failed",
>BR_FAILED_REPLY);
> -   binder_free_buf(proc, buffer);
> +   binder_free_buf(proc, thread, buffer);
> binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
>  "%d:%d %stransaction %d fd fixups failed 
> %d/%d, line %d\n",
>  proc->pid, thread->pid,
> --
> 2.33.0.259.gc128427fd7-goog
>
>
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Re: [PATCH] binder: make sure fd closes complete

2021-08-31 Thread Christian Brauner
On Mon, Aug 30, 2021 at 12:51:46PM -0700, Todd Kjos wrote:
> During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object
> cleanup may close 1 or more fds. The close operations are
> completed using the task work mechanism -- which means the thread
> needs to return to userspace or the file object may never be
> dereferenced -- which can lead to hung processes.
> 
> Force the binder thread back to userspace if an fd is closed during
> BC_FREE_BUFFER handling.
> 
> Signed-off-by: Todd Kjos 
> ---

Looks good. Thanks!
Acked-by: Christian Brauner 
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