From 5e5adb0e04e65d7976eb7c8a915ddc0016d692e4 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Sat, 30 Mar 2024 19:01:14 +0000 Subject: [PATCH] FROMLIST: binder: check offset alignment in binder_get_object() 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: Acked-by: Todd Kjos Signed-off-by: Carlos Llamas Bug: 320661088 Link: https://lore.kernel.org/all/20240330190115.1877819-1-cmllamas@google.com/ Signed-off-by: Carlos Llamas Change-Id: Iaddabaa28de7ba7b7d35dbb639d38ca79dbc5077 (cherry picked from commit 0c9784b747c6a960e5b922e9ccff382db1b73ce4) Signed-off-by: Lee Jones --- 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 cc6c9ceca866..30daf243f738 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1891,8 +1891,10 @@ 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;