From: Alessandro Astone <ales.astone@gmail.com> stable inclusion from stable-v5.10.157 commit ae9e0cc973fb7499ea1b1a8dfd0795f728b84faf category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6DKVG CVE: CVE-2023-20938 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit ef38de9217a04c9077629a24652689d8fdb4c6c6 upstream. Some android userspace is sending BINDER_TYPE_FDA objects with num_fds=0. Like the previous patch, this is reproducible when playing a video. Before commit 09184ae9b575 BINDER_TYPE_FDA objects with num_fds=0 were 'correctly handled', as in no fixup was performed. After commit 09184ae9b575 we aggregate fixup and skip regions in binder_ptr_fixup structs and distinguish between the two by using the skip_size field: if it's 0, then it's a fixup, otherwise skip. When processing BINDER_TYPE_FDA objects with num_fds=0 we add a skip region of skip_size=0, and this causes issues because now binder_do_deferred_txn_copies will think this was a fixup region. To address that, return early from binder_translate_fd_array to avoid adding an empty skip region. Fixes: 09184ae9b575 ("binder: defer copies of pre-patched txn data") Acked-by: Todd Kjos <tkjos@google.com> Cc: stable <stable@kernel.org> Signed-off-by: Alessandro Astone <ales.astone@gmail.com> Link: https://lore.kernel.org/r/20220415120015.52684-1-ales.astone@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Carlos Llamas <cmllamas@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Li Huafei <lihuafei1@huawei.com> Reviewed-by: Zheng Yejian <zhengyejian1@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> --- drivers/android/binder.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 0fc6b3e2761a..b403c7f063b0 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2891,6 +2891,9 @@ static int binder_translate_fd_array(struct list_head *pf_head, struct binder_proc *proc = thread->proc; int ret; + if (fda->num_fds == 0) + return 0; + fd_buf_size = sizeof(u32) * fda->num_fds; if (fda->num_fds >= SIZE_MAX / sizeof(u32)) { binder_user_error("%d:%d got transaction with invalid number of fds (%lld)\n", -- 2.25.1