This is a note to let you know that I've just added the patch titled
ANDROID: binder: Add strong ref checks
to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 0a3ffab93fe52530602fe47cd74802cffdb19c05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= <arve@xxxxxxxxxxx>
Date: Mon, 24 Oct 2016 15:20:29 +0200
Subject: 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.
Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>
Signed-off-by: Martijn Coenen <maco@xxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/android/binder.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 562af94bec35..3681759c22d7 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1002,7 +1002,7 @@ 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)
+ u32 desc, bool need_strong_ref)
{
struct rb_node *n = proc->refs_by_desc.rb_node;
struct binder_ref *ref;
@@ -1010,12 +1010,16 @@ 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;
}
@@ -1285,7 +1289,10 @@ 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;
+
+ ref = binder_get_ref(proc, fp->handle,
+ fp->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
pr_err("transaction release %d bad handle %d\n",
@@ -1380,7 +1387,7 @@ 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);
@@ -1589,7 +1596,10 @@ 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;
+
+ 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",
@@ -1800,7 +1810,9 @@ 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);
@@ -1996,7 +2008,7 @@ static int binder_thread_write(struct binder_proc *proc,
if (get_user(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,
--
2.10.1
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