On Thu, Nov 16, 2017 at 09:56:50AM -0800, Todd Kjos wrote:
> proc->files cleanup is initiated by binder_vma_close. Therefore
> a reference on the binder_proc is not enough to prevent the
> files_struct from being released while the binder_proc still has
> a reference. This can lead to an attempt to dereference the
> stale pointer obtained from proc->files prior to proc->files
> cleanup. This has been seen once in task_get_unused_fd_flags()
> when __alloc_fd() is called with a stale "files".
>
> The fix is to always use get_files_struct() to obtain struct_files
> so that the refcount on the files_struct is used to prevent
> a premature free. proc->files is removed since we get it every
> time.
>
> Signed-off-by: Todd Kjos <[email protected]>
> ---
> drivers/android/binder.c | 63 +++++++++++++++++++++++-------------------------
> 1 file changed, 30 insertions(+), 33 deletions(-)
For a v2 patch (or v3 or whatever), you need to put below the --- line
what changed from the previous version(s).
Documentation/SubmittingPatches describes this pretty well :)
thanks,
greg k-h
From 1584271463192671265@xxx Fri Nov 17 00:36:44 +0000 2017
X-GM-THRID: 1584246731040362261
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread
Sorry about that, do you want a v3 with correct annotations?
On Thu, Nov 16, 2017 at 12:27 PM, Greg KH <[email protected]> wrote:
> On Thu, Nov 16, 2017 at 09:56:50AM -0800, Todd Kjos wrote:
>> proc->files cleanup is initiated by binder_vma_close. Therefore
>> a reference on the binder_proc is not enough to prevent the
>> files_struct from being released while the binder_proc still has
>> a reference. This can lead to an attempt to dereference the
>> stale pointer obtained from proc->files prior to proc->files
>> cleanup. This has been seen once in task_get_unused_fd_flags()
>> when __alloc_fd() is called with a stale "files".
>>
>> The fix is to always use get_files_struct() to obtain struct_files
>> so that the refcount on the files_struct is used to prevent
>> a premature free. proc->files is removed since we get it every
>> time.
>>
>> Signed-off-by: Todd Kjos <[email protected]>
>> ---
>> drivers/android/binder.c | 63 +++++++++++++++++++++++-------------------------
>> 1 file changed, 30 insertions(+), 33 deletions(-)
>
> For a v2 patch (or v3 or whatever), you need to put below the --- line
> what changed from the previous version(s).
> Documentation/SubmittingPatches describes this pretty well :)
>
> thanks,
>
> greg k-h
From 1584246731040362261@xxx Thu Nov 16 18:03:38 +0000 2017
X-GM-THRID: 1584246731040362261
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread