From d5cf5b37064b1699d946e8b7ab4ac7d7d101814c Mon Sep 17 00:00:00 2001 From: Jens Wiklander Date: Fri, 19 Sep 2025 10:48:31 +0200 Subject: [PATCH] tee: fix register_shm_helper() 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 Closes: https://lore.kernel.org/op-tee/CACOXgS-Bo2W72Nj1_44c7bntyNYOavnTjJAvUbEiQfq=u9W+-g@mail.gmail.com/ Tested-by: Masami Ichikawa Fixes: 7bdee4157591 ("tee: Use iov_iter to better support shared buffer registration") Signed-off-by: Jens Wiklander --- drivers/tee/tee_shm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index daf6e5cfd59ae..76c54e1dc98c3 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -319,6 +319,14 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, if (unlikely(len <= 0)) { ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM); goto err_free_shm_pages; + } else if (DIV_ROUND_UP(len + off, PAGE_SIZE) != num_pages) { + /* + * 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; } /* -- 2.47.3