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authorOla Jeppsson <ola@snap.com>2022-11-24 17:49:41 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-01-20 13:23:11 +0100
commit96b328d119eca7563c1edcc4e1039a62e6370ecb (patch)
treececce8647d755950e5896402c06182daac45f3ce /drivers
parent5bb96c8f9268e2fdb0e5321cbc358ee5941efc15 (diff)
misc: fastrpc: Fix use-after-free race condition for maps
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: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") Cc: stable <stable@kernel.org> Signed-off-by: Ola Jeppsson <ola@snap.com> Signed-off-by: Abel Vesa <abel.vesa@linaro.org> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Link: https://lore.kernel.org/r/20221124174941.418450-4-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/misc/fastrpc.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 9f8d52b59ed2..a2a1258531d0 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -350,10 +350,12 @@ 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;
}