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platform: goldfish: pipe: Prevent memory corruption from several threads writing to the same variable

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Move the "pages" buffer into "struct goldfish_pipe". Since we are
locking the mutex on the pipe in transfer_max_buffers, other threads
willnot be able to write into it, but other pipe instances could be
served because they have its own buffer.

Signed-off-by: Roman Kiryanov <rkir@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Roman Kiryanov 2018-09-14 10:51:03 -07:00 committed by Greg Kroah-Hartman
parent 9b9a4a3f14
commit 48a2d422b5
1 changed files with 14 additions and 10 deletions
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24
drivers/platform/goldfish/goldfish_pipe.c
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@ -163,6 +163,9 @@ struct goldfish_pipe {
/* Pointer to the parent goldfish_pipe_dev instance */
struct goldfish_pipe_dev *dev;
/* A buffer of pages, too large to fit into a stack frame */
struct page *pages[MAX_BUFFERS_PER_COMMAND];
};
/* The global driver data. Holds a reference to the i/o page used to
@ -340,21 +343,23 @@ static int transfer_max_buffers(struct goldfish_pipe *pipe,
s32 *consumed_size,
int *status)
{
static struct page *pages[MAX_BUFFERS_PER_COMMAND];
unsigned long first_page = address & PAGE_MASK;
unsigned int iter_last_page_size;
int pages_count = pin_user_pages(first_page, last_page,
last_page_size, is_write,
pages, &iter_last_page_size);
if (pages_count < 0)
return pages_count;
int pages_count;
/* Serialize access to the pipe command buffers */
if (mutex_lock_interruptible(&pipe->lock))
return -ERESTARTSYS;
populate_rw_params(pages, pages_count, address, address_end,
pages_count = pin_user_pages(first_page, last_page,
last_page_size, is_write,
pipe->pages, &iter_last_page_size);
if (pages_count < 0) {
mutex_unlock(&pipe->lock);
return pages_count;
}
populate_rw_params(pipe->pages, pages_count, address, address_end,
first_page, last_page, iter_last_page_size, is_write,
pipe->command_buffer);
@ -364,10 +369,9 @@ static int transfer_max_buffers(struct goldfish_pipe *pipe,
*consumed_size = pipe->command_buffer->rw_params.consumed_size;
release_user_pages(pages, pages_count, is_write, *consumed_size);
release_user_pages(pipe->pages, pages_count, is_write, *consumed_size);
mutex_unlock(&pipe->lock);
return 0;
}