In register_shm_helper(), fix incorrect error handling for a call to iov_iter_extract_pages(). A case is missing for when iov_iter_extract_pages() only got some pages and return a number larger than 0, but not the requested amount.

This fixes a possible NULL pointer dereference following a bad input from ioctl(TEE_IOC_SHM_REGISTER) where parts of the buffer isn't mapped.

Cc: stable@vger.kernel.org Reported-by: Masami Ichikawa masami256@gmail.com Closes: https://lore.kernel.org/op-tee/CACOXgS-Bo2W72Nj1_44c7bntyNYOavnTjJAvUbEiQfq=... Fixes: 7bdee4157591 ("tee: Use iov_iter to better support shared buffer registration") Signed-off-by: Jens Wiklander jens.wiklander@linaro.org --- drivers/tee/tee_shm.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index daf6e5cfd59a..6ed7d030f4ed 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -316,7 +316,16 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags,

len = iov_iter_extract_pages(iter, &shm->pages, LONG_MAX, num_pages, 0, &off); - if (unlikely(len <= 0)) { + if (DIV_ROUND_UP(len + off, PAGE_SIZE) != num_pages) { + if (len > 0) { + /* + * If we only got a few pages, update to release + * the correct amount below. + */ + shm->num_pages = len / PAGE_SIZE; + ret = ERR_PTR(-ENOMEM); + goto err_put_shm_pages; + } ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM); goto err_free_shm_pages; }