[PATCH] staging: r8188eu: fix a memory leak in rtw_mp_pwrtrk()

[Jianglei Nie]

Line 5968 (#1) allocates a memory chunk for input by kmalloc().
Line 5973 (#2), line 5989 (#4) and line 5994 (#5) free the input
before the function returns while line 5986 (#3) forget to free it,
which will lead to a memory leak. This bug influences all stable
versions from 5.15.1 to 5.15.7.

We should kfree() input in line 5986 (#3).

5960 static int rtw_mp_pwrtrk(struct net_device *dev,
5961 			struct iw_request_info *info,
5962 			struct iw_point *wrqu, char *extra)
5963 {
5968 	char	*input = kmalloc(wrqu->length, GFP_KERNEL);
	// #1: kmalloc space
5970 	if (!input)
5971 		return -ENOMEM;
5972 	if (copy_from_user(input, wrqu->pointer, wrqu->length)) {
5973 		kfree(input); // #2: kfree space
5974 		return -EFAULT;
5975	}

5980	if (strncmp(input, "stop", 4) == 0) {
5981		enable = 0;
5982		sprintf(extra, "mp tx power tracking stop");
5983	} else if (sscanf(input, "ther =%d", &thermal)) {
5984		ret = Hal_SetThermalMeter(padapter, (u8)thermal);
5985		if (ret == _FAIL)
5986			return -EPERM; // #3: missing kfree
5987		sprintf(extra, "mp tx power tracking start,
			target value =%d ok ", thermal);
5988	} else {
5989		kfree(input); // #4: kfree space
5990		return -EINVAL;
5991	}

5994	kfree(input); // #5: kfree space

6000	return 0;
6001 }

Signed-off-by: Jianglei Nie <niejianglei2021@xxxxxxx>
---
 drivers/staging/r8188eu/os_dep/ioctl_linux.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/r8188eu/os_dep/ioctl_linux.c b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
index 0eccce57c63a..906a57eae1af 100644
--- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
+++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
@@ -5982,8 +5982,10 @@ static int rtw_mp_pwrtrk(struct net_device *dev,
 			sprintf(extra, "mp tx power tracking stop");
 		} else if (sscanf(input, "ther =%d", &thermal)) {
 				ret = Hal_SetThermalMeter(padapter, (u8)thermal);
-				if (ret == _FAIL)
+				if (ret == _FAIL) {
+					kfree(input);
 					return -EPERM;
+				}
 				sprintf(extra, "mp tx power tracking start, target value =%d ok ", thermal);
 		} else {
 			kfree(input);
-- 
2.25.1