diff options
| author | Ola Jeppsson <ola@snap.com> | 2022-11-24 17:49:41 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-20 13:23:11 +0100 |
| commit | 96b328d119eca7563c1edcc4e1039a62e6370ecb (patch) | |
| tree | cecce8647d755950e5896402c06182daac45f3ce /drivers/misc | |
| parent | 5bb96c8f9268e2fdb0e5321cbc358ee5941efc15 (diff) | |
| download | lwn-96b328d119eca7563c1edcc4e1039a62e6370ecb.tar.gz lwn-96b328d119eca7563c1edcc4e1039a62e6370ecb.zip | |
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/misc')
| -rw-r--r-- | drivers/misc/fastrpc.c | 8 |
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; } |