From: Abel Vesa <abel.vesa@linaro.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Amol Maheshwari <amahesh@qti.qualcomm.com>,
Ekansh Gupta <ekangupt@qti.qualcomm.com>,
Vamsi Krishna Gattupalli <quic_vgattupa@quicinc.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-arm-msm@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ola Jeppsson <ola@snap.com>
Subject: [PATCH 3/3] misc: fastrpc: Fix use-after-free race condition for maps
Date: Fri, 2 Sep 2022 18:14:23 +0300 [thread overview]
Message-ID: <20220902151423.3351414-3-abel.vesa@linaro.org> (raw)
In-Reply-To: <20220902151423.3351414-1-abel.vesa@linaro.org>
From: Ola Jeppsson <ola@snap.com>
It is possible that in between calling fastrpc_map_get() until
map->fl->lock is taken in fastrpc_free_map(), another thread can call
fastrpc_map_lookup() and get a reference to a map that is about to be
deleted.
Rewrite fastrpc_map_get() to only increase the reference count of a map
if it's non-zero. Propagate this to callers so they can know if a map is
about to be deleted.
Fixes this warning:
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 5 PID: 10100 at lib/refcount.c:25 refcount_warn_saturate
...
Call trace:
refcount_warn_saturate
[fastrpc_map_get inlined]
[fastrpc_map_lookup inlined]
fastrpc_map_create
fastrpc_internal_invoke
fastrpc_device_ioctl
__arm64_sys_ioctl
invoke_syscall
Fixes: c68cfb718c8f9 ("misc: fastrpc: Add support for context Invoke method")
Signed-off-by: Ola Jeppsson <ola@snap.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
drivers/misc/fastrpc.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 50c17f5da3a8..58654d394d17 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -332,10 +332,12 @@ static void fastrpc_map_put(struct fastrpc_map *map)
kref_put(&map->refcount, fastrpc_free_map);
}
-static void fastrpc_map_get(struct fastrpc_map *map)
+static int fastrpc_map_get(struct fastrpc_map *map)
{
- if (map)
- kref_get(&map->refcount);
+ if (!map)
+ return -ENOENT;
+
+ return kref_get_unless_zero(&map->refcount) ? 0 : -ENOENT;
}
--
2.34.1
next prev parent reply other threads:[~2022-09-02 15:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-02 15:14 [PATCH 1/3] misc: fastrpc: Fix use-after-free and race in fastrpc_map_find Abel Vesa
2022-09-02 15:14 ` [PATCH 2/3] misc: fastrpc: Don't remove map on creater_process and device_release Abel Vesa
2022-09-22 22:46 ` Srinivas Kandagatla
2022-09-02 15:14 ` Abel Vesa [this message]
2022-09-22 22:45 ` [PATCH 3/3] misc: fastrpc: Fix use-after-free race condition for maps Srinivas Kandagatla
2022-09-22 22:46 ` [PATCH 1/3] misc: fastrpc: Fix use-after-free and race in fastrpc_map_find Srinivas Kandagatla
2022-11-24 17:49 [PATCH 0/3] misc: fastrpc: fixes for 6.1 Srinivas Kandagatla
2022-11-24 17:49 ` [PATCH 3/3] misc: fastrpc: Fix use-after-free race condition for maps Srinivas Kandagatla
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