From 46d6ee12fa9dc094193b06be3d4db236cfa564a9 Mon Sep 17 00:00:00 2001 From: Etienne Carriere Date: Sun, 29 Apr 2018 14:22:29 +0200 Subject: [PATCH] tee: check shm references are consistent in offset/size [ Upstream commit ab9d3db5b320a052452b9cd035599ee3c84bbee9 ] This change prevents userland from referencing TEE shared memory outside the area initially allocated by its owner. Prior this change an application could not reference or access memory it did not own but it could reference memory not explicitly allocated by owner but still allocated to the owner due to the memory allocation granule. Reported-by: Alexandre Jutras Signed-off-by: Etienne Carriere Signed-off-by: Jens Wiklander Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/tee/tee_core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 58a5009..a548c36 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -181,6 +181,17 @@ static int params_from_user(struct tee_context *ctx, struct tee_param *params, if (IS_ERR(shm)) return PTR_ERR(shm); + /* + * Ensure offset + size does not overflow offset + * and does not overflow the size of the referred + * shared memory object. + */ + if ((ip.a + ip.b) < ip.a || + (ip.a + ip.b) > shm->size) { + tee_shm_put(shm); + return -EINVAL; + } + params[n].u.memref.shm_offs = ip.a; params[n].u.memref.size = ip.b; params[n].u.memref.shm = shm; -- 2.7.4