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https://github.com/Divested-Mobile/DivestOS-Build.git
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89 lines
2.9 KiB
Diff
89 lines
2.9 KiB
Diff
From a5e46d8635a2e28463b365aacdeab6750abd0d49 Mon Sep 17 00:00:00 2001
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From: Sahitya Tummala <stummala@codeaurora.org>
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Date: Fri, 3 Feb 2017 13:24:19 +0530
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Subject: uio: fix potential use after free issue when accessing debug_buffer
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The variable debug_buffer is a global variable which is allocated
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and free'd when open/close is called on debugfs file -
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"/sys/kernel/debug/rmt_storage/info". The current code doesn't
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have locks to handle concurrent accesses to the above file.
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This results into use after free issue when debug_buffer is
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accessed by two threads at the same time. Fix this by adding
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a mutex lock to protect this global variable.
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Change-Id: I6bc3f0ae2d7fca3ca9fe8561612f5863b6c3268a
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Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
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---
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drivers/uio/msm_sharedmem/sharedmem_qmi.c | 17 ++++++++++++++---
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1 file changed, 14 insertions(+), 3 deletions(-)
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diff --git a/drivers/uio/msm_sharedmem/sharedmem_qmi.c b/drivers/uio/msm_sharedmem/sharedmem_qmi.c
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index 48fb17e..fd95dee 100644
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--- a/drivers/uio/msm_sharedmem/sharedmem_qmi.c
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+++ b/drivers/uio/msm_sharedmem/sharedmem_qmi.c
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@@ -1,4 +1,4 @@
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-/* Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
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+/* Copyright (c) 2014-2015, 2017, The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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@@ -223,6 +223,7 @@ static int sharedmem_qmi_req_cb(struct qmi_handle *handle, void *conn_h,
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#define DEBUG_BUF_SIZE (2048)
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static char *debug_buffer;
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static u32 debug_data_size;
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+static struct mutex dbg_buf_lock; /* mutex for debug_buffer */
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static ssize_t debug_read(struct file *file, char __user *buf,
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size_t count, loff_t *file_pos)
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@@ -279,21 +280,29 @@ static int debug_open(struct inode *inode, struct file *file)
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{
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u32 buffer_size;
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- if (debug_buffer != NULL)
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+ mutex_lock(&dbg_buf_lock);
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+ if (debug_buffer != NULL) {
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+ mutex_unlock(&dbg_buf_lock);
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return -EBUSY;
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+ }
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buffer_size = DEBUG_BUF_SIZE;
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debug_buffer = kzalloc(buffer_size, GFP_KERNEL);
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- if (debug_buffer == NULL)
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+ if (debug_buffer == NULL) {
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+ mutex_unlock(&dbg_buf_lock);
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return -ENOMEM;
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+ }
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debug_data_size = fill_debug_info(debug_buffer, buffer_size);
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+ mutex_unlock(&dbg_buf_lock);
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return 0;
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}
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static int debug_close(struct inode *inode, struct file *file)
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{
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+ mutex_lock(&dbg_buf_lock);
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kfree(debug_buffer);
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debug_buffer = NULL;
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debug_data_size = 0;
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+ mutex_unlock(&dbg_buf_lock);
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return 0;
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}
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@@ -324,6 +333,7 @@ static void debugfs_init(void)
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{
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struct dentry *f_ent;
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+ mutex_init(&dbg_buf_lock);
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dir_ent = debugfs_create_dir("rmt_storage", NULL);
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if (IS_ERR(dir_ent)) {
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pr_err("Failed to create debug_fs directory\n");
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@@ -352,6 +362,7 @@ static void debugfs_init(void)
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static void debugfs_exit(void)
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{
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debugfs_remove_recursive(dir_ent);
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+ mutex_destroy(&dbg_buf_lock);
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}
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static void sharedmem_qmi_svc_recv_msg(struct work_struct *work)
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--
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cgit v1.1
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