openat2: explicitly return -E2BIG for (usize > PAGE_SIZE)

commit f92f0a1b05698340836229d791b3ffecc71b265a upstream.

While we do currently return -EFAULT in this case, it seems prudent to
follow the behaviour of other syscalls like clone3. It seems quite
unlikely that anyone depends on this error code being EFAULT, but we can
always revert this if it turns out to be an issue.

Cc: stable@vger.kernel.org # v5.6+
Fixes: fddb5d430ad9 ("open: introduce openat2(2) syscall")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/r/20241010-extensible-structs-check_fields-v3-3-d2833dfe6edd@cyphar.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/open.c b/fs/open.c
index 694110929519cdde6f72af76f0c93457fc9fa92e..7bcc26b14cd798a50bcf5ebe12cb128c6623dc62 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -1270,6 +1270,8 @@ SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
 
        if (unlikely(usize < OPEN_HOW_SIZE_VER0))
                return -EINVAL;
+       if (unlikely(usize > PAGE_SIZE))
+               return -E2BIG;
 
        err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
        if (err)