fuzz: Comply with new guest memory requirement for page alignment

When the input's length is not page aligned, round it up. This allows
the fuzzer to provide more random inputs without causing the `unwrap`
call to trigger false positives when creating guest memory.

BUG=chromium:972172
TEST=run fuzz case from the bug

Change-Id: Iaf8f2ba943f38b90e168301dbb8c15dee5ee45c8
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1659626
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fuzz/zimage_fuzzer.rs b/fuzz/zimage_fuzzer.rs
index f4aeb3f..d94a53d 100644
--- a/fuzz/zimage_fuzzer.rs
+++ b/fuzz/zimage_fuzzer.rs
@@ -4,7 +4,7 @@
 
 #![no_main]
 
-use sys_util::{GuestAddress, GuestMemory, SharedMemory};
+use sys_util::{round_up_to_page_size, GuestAddress, GuestMemory, SharedMemory};
 
 use std::fs::File;
 use std::io::Write;
@@ -30,7 +30,9 @@ pub fn test_one_input(data: *const u8, size: usize) -> i32 {
         // function.
         let bytes = unsafe { slice::from_raw_parts(data, size) };
         let mut kimage = make_elf_bin(bytes);
-        let mem = GuestMemory::new(&[(GuestAddress(0), bytes.len() as u64 + 0x1000)]).unwrap();
+        // `GuestMemory` only accepts page aligned segments.
+        let len = round_up_to_page_size(bytes.len()) as u64;
+        let mem = GuestMemory::new(&[(GuestAddress(0), len)]).unwrap();
         let _ = kernel_loader::load_kernel(&mem, GuestAddress(0), &mut kimage);
     })
     .err()