From: Carlos Llamas cmllamas@google.com

mainline inclusion from mainline-v6.9-rc5 commit aaef73821a3b0194a01bd23ca77774f704a04d40 category: bugfix bugzilla: 189856 CVE: CVE-2024-26926

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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@vger.kernel.org Signed-off-by: Carlos Llamas cmllamas@google.com Acked-by: Todd Kjos tkjos@google.com Link: https://lore.kernel.org/r/20240330190115.1877819-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Lin Yujun linyujun809@huawei.com --- drivers/android/binder.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c index f98d84c5c695..723e5a919c20 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2077,8 +2077,10 @@ static size_t binder_get_object(struct binder_proc *proc, size_t object_size = 0;

read_size = min_t(size_t, sizeof(*object), buffer->data_size - offset); - if (offset > buffer->data_size || read_size < sizeof(*hdr)) + if (offset > buffer->data_size || read_size < sizeof(*hdr) || + !IS_ALIGNED(offset, sizeof(u32))) return 0; + if (u) { if (copy_from_user(object, u + offset, read_size)) return 0;