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Date: Fri, 1 Dec 2023 17:21:40 +0000
From: Carlos Llamas <cmllamas@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Arve Hjønnevåg" <arve@...roid.com>,
Todd Kjos <tkjos@...roid.com>,
Martijn Coenen <maco@...roid.com>,
Joel Fernandes <joel@...lfernandes.org>,
Christian Brauner <brauner@...nel.org>,
Carlos Llamas <cmllamas@...gle.com>,
Suren Baghdasaryan <surenb@...gle.com>
Cc: linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: [PATCH v2 11/28] binder: do unlocked work in binder_alloc_new_buf()
Extract non-critical sections from binder_alloc_new_buf_locked() that
don't require holding the alloc->mutex. While we are here, consolidate
the checks for size overflow and zero-sized padding into a separate
sanitized_size() helper function.
Also add a few touchups to follow the coding guidelines.
Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
---
drivers/android/binder_alloc.c | 95 ++++++++++++++++++++--------------
1 file changed, 56 insertions(+), 39 deletions(-)
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 3051ea7ca44f..40a2ca0c0dea 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -363,9 +363,7 @@ static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
static struct binder_buffer *binder_alloc_new_buf_locked(
struct binder_alloc *alloc,
- size_t data_size,
- size_t offsets_size,
- size_t extra_buffers_size,
+ size_t size,
int is_async,
int pid)
{
@@ -373,39 +371,10 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
struct binder_buffer *buffer;
size_t buffer_size;
struct rb_node *best_fit = NULL;
- size_t size, data_offsets_size;
unsigned long has_page_addr;
unsigned long end_page_addr;
int ret;
- /* Check binder_alloc is fully initialized */
- if (!binder_alloc_get_vma(alloc)) {
- binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
- "%d: binder_alloc_buf, no vma\n",
- alloc->pid);
- return ERR_PTR(-ESRCH);
- }
-
- data_offsets_size = ALIGN(data_size, sizeof(void *)) +
- ALIGN(offsets_size, sizeof(void *));
-
- if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
- binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
- "%d: got transaction with invalid size %zd-%zd\n",
- alloc->pid, data_size, offsets_size);
- return ERR_PTR(-EINVAL);
- }
- size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
- if (size < data_offsets_size || size < extra_buffers_size) {
- binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
- "%d: got transaction with invalid extra_buffers_size %zd\n",
- alloc->pid, extra_buffers_size);
- return ERR_PTR(-EINVAL);
- }
-
- /* Pad 0-size buffers so they get assigned unique addresses */
- size = max(size, sizeof(void *));
-
if (is_async && alloc->free_async_space < size) {
binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
"%d: binder_alloc_buf size %zd failed, no async space left\n",
@@ -421,13 +390,14 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
if (size < buffer_size) {
best_fit = n;
n = n->rb_left;
- } else if (size > buffer_size)
+ } else if (size > buffer_size) {
n = n->rb_right;
- else {
+ } else {
best_fit = n;
break;
}
}
+
if (best_fit == NULL) {
size_t allocated_buffers = 0;
size_t largest_alloc_size = 0;
@@ -505,10 +475,7 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
"%d: binder_alloc_buf size %zd got %pK\n",
alloc->pid, size, buffer);
- buffer->data_size = data_size;
- buffer->offsets_size = offsets_size;
buffer->async_transaction = is_async;
- buffer->extra_buffers_size = extra_buffers_size;
buffer->pid = pid;
buffer->oneway_spam_suspect = false;
if (is_async) {
@@ -527,6 +494,7 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
alloc->oneway_spam_detected = false;
}
}
+
return buffer;
err_alloc_buf_struct_failed:
@@ -535,6 +503,28 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
return ERR_PTR(-ENOMEM);
}
+/* Calculate the sanitized total size, returns 0 for invalid request */
+static inline size_t sanitized_size(size_t data_size,
+ size_t offsets_size,
+ size_t extra_buffers_size)
+{
+ size_t total, tmp;
+
+ /* Align to pointer size and check for overflows */
+ tmp = ALIGN(data_size, sizeof(void *)) +
+ ALIGN(offsets_size, sizeof(void *));
+ if (tmp < data_size || tmp < offsets_size)
+ return 0;
+ total = tmp + ALIGN(extra_buffers_size, sizeof(void *));
+ if (total < tmp || total < extra_buffers_size)
+ return 0;
+
+ /* Pad 0-sized buffers so they get a unique address */
+ total = max(total, sizeof(void *));
+
+ return total;
+}
+
/**
* binder_alloc_new_buf() - Allocate a new binder buffer
* @alloc: binder_alloc for this proc
@@ -559,11 +549,38 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
int pid)
{
struct binder_buffer *buffer;
+ size_t size;
+
+ /* Check binder_alloc is fully initialized */
+ if (!binder_alloc_get_vma(alloc)) {
+ binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
+ "%d: binder_alloc_buf, no vma\n",
+ alloc->pid);
+ return ERR_PTR(-ESRCH);
+ }
+
+ size = sanitized_size(data_size, offsets_size, extra_buffers_size);
+ if (unlikely(!size)) {
+ binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+ "%d: got transaction with invalid size %zd-%zd-%zd\n",
+ alloc->pid, data_size, offsets_size,
+ extra_buffers_size);
+ return ERR_PTR(-EINVAL);
+ }
mutex_lock(&alloc->mutex);
- buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
- extra_buffers_size, is_async, pid);
+ buffer = binder_alloc_new_buf_locked(alloc, size, is_async, pid);
+ if (IS_ERR(buffer)) {
+ mutex_unlock(&alloc->mutex);
+ goto out;
+ }
+
+ buffer->data_size = data_size;
+ buffer->offsets_size = offsets_size;
+ buffer->extra_buffers_size = extra_buffers_size;
mutex_unlock(&alloc->mutex);
+
+out:
return buffer;
}
--
2.43.0.rc2.451.g8631bc7472-goog
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