From c4a0b63b575eeea1dcc2918be283204a16d19cfe Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= Date: Tue, 2 Aug 2016 15:40:39 -0700 Subject: [PATCH] ANDROID: binder: Add strong ref checks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Prevent using a binder_ref with only weak references where a strong reference is required. BUG: 30445380 Signed-off-by: Arve Hjønnevåg Git-repo: https://android.googlesource.com/kernel/msm.git Git-commit: 5e2a2bc89956ae1c739854403408059144b23c28 Signed-off-by: Ravi Kumar Siddojigari Change-Id: I66c15b066808f28bd27bfe50fd0e03ff45a09fca Signed-off-by: Ravi Kumar Siddojigari --- drivers/android/binder.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index f80cfc36a354..16fa3593b666 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1074,7 +1074,7 @@ static int binder_dec_node(struct binder_node *node, int strong, int internal) static struct binder_ref *binder_get_ref(struct binder_proc *proc, - uint32_t desc) + uint32_t desc, bool need_strong_ref) { struct rb_node *n = proc->refs_by_desc.rb_node; struct binder_ref *ref; @@ -1082,12 +1082,16 @@ static struct binder_ref *binder_get_ref(struct binder_proc *proc, while (n) { ref = rb_entry(n, struct binder_ref, rb_node_desc); - if (desc < ref->desc) + if (desc < ref->desc) { n = n->rb_left; - else if (desc > ref->desc) + } else if (desc > ref->desc) { n = n->rb_right; - else + } else if (need_strong_ref && !ref->strong) { + binder_user_error("tried to use weak ref as strong ref\n"); + return NULL; + } else { return ref; + } } return NULL; } @@ -1357,7 +1361,8 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { pr_err("transaction release %d bad handle %d\n", @@ -1452,7 +1457,7 @@ static void binder_transaction(struct binder_proc *proc, if (tr->target.handle) { struct binder_ref *ref; - ref = binder_get_ref(proc, tr->target.handle); + ref = binder_get_ref(proc, tr->target.handle, true); if (ref == NULL) { binder_user_error("%d:%d got transaction to invalid handle\n", proc->pid, thread->pid); @@ -1661,7 +1666,8 @@ static void binder_transaction(struct binder_proc *proc, } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { binder_user_error("%d:%d got transaction with invalid handle, %d\n", @@ -1880,7 +1886,9 @@ static int binder_thread_write(struct binder_proc *proc, ref->desc); } } else - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, + cmd == BC_ACQUIRE || + cmd == BC_RELEASE); if (ref == NULL) { binder_user_error("%d:%d refcount change on invalid ref %d\n", proc->pid, thread->pid, target); @@ -2076,7 +2084,7 @@ static int binder_thread_write(struct binder_proc *proc, if (get_user_preempt_disabled(cookie, (binder_uintptr_t __user *)ptr)) return -EFAULT; ptr += sizeof(binder_uintptr_t); - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, false); if (ref == NULL) { binder_user_error("%d:%d %s invalid ref %d\n", proc->pid, thread->pid,