Commit 50548d37 authored by Ola Jeppsson's avatar Ola Jeppsson Committed by Lin Ruifeng
Browse files

misc: fastrpc: Fix use-after-free race condition for maps 

stable inclusion
from stable-v5.10.165
commit b171d0d2cf1b8387c72c8d325c5d5746fa271e39
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IALICT
CVE: CVE-2022-48872

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b171d0d2cf1b8387c72c8d325c5d5746fa271e39



--------------------------------

commit 96b328d1 upstream.

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: c68cfb71 ("misc: fastrpc: Add support for context Invoke method")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarOla Jeppsson <ola@snap.com>
Signed-off-by: default avatarAbel Vesa <abel.vesa@linaro.org>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221124174941.418450-4-srinivas.kandagatla@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarLin Ruifeng <linruifeng4@huawei.com>
parent aac3c2e2

drivers/misc/fastrpc.c

+5 −3
Original line number Diff line number Diff line
@@ -263,10 +263,12 @@ 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;

}



static int fastrpc_map_find(struct fastrpc_user *fl, int fd,