linux-kernel - [PATCH 4.9 9/9] ion: Do not put ION handle until after its final use

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220127180257.527413926@linuxfoundation.org>
Date:   Thu, 27 Jan 2022 19:08:27 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, lee.jones@...aro.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org
Subject: [PATCH 4.9 9/9] ion: Do not put ION handle until after its final use

From: Lee Jones <lee.jones@...aro.org>

pass_to_user() eventually calls kref_put() on an ION handle which is
still live, potentially allowing for it to be legitimately freed by
the client.

Prevent this from happening before its final use in both ION_IOC_ALLOC
and ION_IOC_IMPORT.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/staging/android/ion/ion-ioctl.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/staging/android/ion/ion-ioctl.c
+++ b/drivers/staging/android/ion/ion-ioctl.c
@@ -165,10 +165,9 @@ long ion_ioctl(struct file *filp, unsign
 				     data.allocation.flags, true);
 		if (IS_ERR(handle))
 			return PTR_ERR(handle);
-		pass_to_user(handle);
 		data.allocation.handle = handle->id;
-
 		cleanup_handle = handle;
+		pass_to_user(handle);
 		break;
 	}
 	case ION_IOC_FREE:
@@ -212,11 +211,12 @@ long ion_ioctl(struct file *filp, unsign
 		if (IS_ERR(handle)) {
 			ret = PTR_ERR(handle);
 		} else {
+			data.handle.handle = handle->id;
 			handle = pass_to_user(handle);
-			if (IS_ERR(handle))
+			if (IS_ERR(handle)) {
 				ret = PTR_ERR(handle);
-			else
-				data.handle.handle = handle->id;
+				data.handle.handle = 0;
+			}
 		}
 		break;
 	}