Re: [PATCH] binder: check offset alignment in binder_get_object()

[Lee Jones]

On Sat, 30 Mar 2024, Carlos Llamas wrote:

> Commit 6d98eb95b450 ("binder: avoid potential data leakage when copying
> txn") introduced changes to how binder objects are copied. In doing so,
> it unintentionally removed an offset alignment check done through calls
> to binder_alloc_copy_from_buffer() -> check_buffer().
> 
> These calls were replaced in binder_get_object() with copy_from_user(),
> so now an explicit offset alignment check is needed here. This avoids
> later complications when unwinding the objects gets harder.
> 
> It is worth noting this check existed prior to commit 7a67a39320df
> ("binder: add function to copy binder object from buffer"), likely
> removed due to redundancy at the time.
> 
> Fixes: 6d98eb95b450 ("binder: avoid potential data leakage when copying txn")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
> ---
>  drivers/android/binder.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Thanks for chasing this one down Carlos.

Reviewed-by: Lee Jones <lee@xxxxxxxxxx>

-- 
Lee Jones [李琼斯]