[PATCH v18 13/15] tee/shm: untag user pointers in tee_shm_register

From: Andrey Konovalov
Date: Mon Jun 24 2019 - 10:33:55 EST

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

tee_shm_register()->optee_shm_unregister()->check_mem_type() uses provided
user pointers for vma lookups (via __check_mem_type()), which can only by
done with untagged pointers.

Untag user pointers in this function.

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
drivers/tee/tee_shm.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 2da026fd12c9..09ddcd06c715 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -254,6 +254,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
shm->teedev = teedev;
shm->ctx = ctx;
shm->id = -1;
+ addr = untagged_addr(addr);
start = rounddown(addr, PAGE_SIZE);
shm->offset = addr - start;
shm->size = length;