[PATCH v2] android/client: Fix memory leak while using realloc()

[PATCH v2] android/client: Fix memory leak while using realloc()

[Atul Rai]

While reallocating space to store additional "remote device set" using
realloc, if realloc() fails, the original block is left untouched but
reference to that block is lost as NULL is assigned to remote_devices.
The original block needs to be freed before return.
---
 android/client/if-bt.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/android/client/if-bt.c b/android/client/if-bt.c
index 4723024..34611b9 100644
--- a/android/client/if-bt.c
+++ b/android/client/if-bt.c
@@ -119,9 +119,18 @@ void add_remote_device(const bt_bdaddr_t *addr)
 	/* Realloc space if needed */
 	if (remote_devices_cnt >= remote_devices_capacity) {
 		remote_devices_capacity *= 2;
+		bt_bdaddr_t *tmp;
+
+		/*
+		 * Save reference to previously allocated memory block so that
+		 * it can be freed in case realloc fails.
+		 */
+		tmp = remote_devices;
+
 		remote_devices = realloc(remote_devices, sizeof(bt_bdaddr_t) *
 						remote_devices_capacity);
 		if (remote_devices == NULL) {
+			free(tmp);
 			remote_devices_capacity = 0;
 			remote_devices_cnt = 0;
 			return;
-- 
2.1.4

Re: [PATCH v2] android/client: Fix memory leak while using realloc()

[Szymon Janc]

Hi Atul,

On Monday 27 of July 2015 09:44:40 Atul Rai wrote:
> While reallocating space to store additional "remote device set" using
> realloc, if realloc() fails, the original block is left untouched but
> reference to that block is lost as NULL is assigned to remote_devices.
> The original block needs to be freed before return.
> ---
>  android/client/if-bt.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/android/client/if-bt.c b/android/client/if-bt.c
> index 4723024..34611b9 100644
> --- a/android/client/if-bt.c
> +++ b/android/client/if-bt.c
> @@ -119,9 +119,18 @@ void add_remote_device(const bt_bdaddr_t *addr)
>  	/* Realloc space if needed */
>  	if (remote_devices_cnt >= remote_devices_capacity) {
>  		remote_devices_capacity *= 2;
> +		bt_bdaddr_t *tmp;
> +
> +		/*
> +		 * Save reference to previously allocated memory block so that
> +		 * it can be freed in case realloc fails.
> +		 */
> +		tmp = remote_devices;
> +
>  		remote_devices = realloc(remote_devices, sizeof(bt_bdaddr_t) *
>  						remote_devices_capacity);
>  		if (remote_devices == NULL) {
> +			free(tmp);
>  			remote_devices_capacity = 0;
>  			remote_devices_cnt = 0;
>  			return;


This doesn't compile cleanly:

  CC       android/client/android_haltest-if-hf-client.o
android/client/if-bt.c: In function ‘add_remote_device’:
android/client/if-bt.c:122:3: error: ISO C90 forbids mixed declarations and 
code [-Werror=declaration-after-statement]
   bt_bdaddr_t *tmp;
   ^
cc1: all warnings being treated as errors
Makefile:6171: recipe for target 'android/client/android_haltest-if-bt.o' 
failed

You can use ./boostrap-configure;make for testing patches as this enables 
extra compiler flags.

-- 
BR
Szymon Janc