Handle possible allocation failure in user_ptr.

Author: wedsonaf

rust/kernel/error.rs

@@ -4,13 +4,9 @@
 //!
 //! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h)
 
-use core::num::TryFromIntError;
-use core::str::Utf8Error;
-
-use alloc::alloc::AllocError;
-
-use crate::bindings;
-use crate::c_types;
+use crate::{bindings, c_types};
+use alloc::{alloc::AllocError, collections::TryReserveError};
+use core::{num::TryFromIntError, str::Utf8Error};
 
 /// Generic integer kernel error.
 ///
@@ -57,6 +53,12 @@ impl From<Utf8Error> for Error {
     }
 }
 
+impl From<TryReserveError> for Error {
+    fn from(_: TryReserveError) -> Error {
+        Error::ENOMEM
+    }
+}
+
 /// A [`Result`] with an [`Error`] error type.
 ///
 /// To be used as the return type for functions that may fail.

rust/kernel/lib.rs

@@ -12,7 +12,7 @@
 //! do so first instead of bypassing this crate.
 
 #![no_std]
-#![feature(allocator_api, alloc_error_handler)]
+#![feature(allocator_api, alloc_error_handler, try_reserve)]
 #![deny(clippy::complexity)]
 #![deny(clippy::correctness)]
 #![deny(clippy::perf)]

rust/kernel/user_ptr.rs

@@ -5,7 +5,7 @@
 //! C header: [`include/linux/uaccess.h`](../../../../include/linux/uaccess.h)
 
 use crate::{c_types, error, KernelResult};
-use alloc::{vec, vec::Vec};
+use alloc::vec::Vec;
 use core::mem::{size_of, MaybeUninit};
 
 extern "C" {
@@ -143,7 +143,9 @@ impl UserSlicePtrReader {
     /// Returns `EFAULT` if the address does not currently point to
     /// mapped, readable memory.
     pub fn read_all(&mut self) -> KernelResult<Vec<u8>> {
-        let mut data = vec![0; self.1];
+        let mut data = Vec::<u8>::new();
+        data.try_reserve_exact(self.1)?;
+        data.resize(self.1, 0);
         // SAFETY: The output buffer is valid as we just allocated it.
         unsafe { self.read_raw(data.as_mut_ptr(), data.len())? };
         Ok(data)