From a40f4ba1a802037b5e3f3cd8257088942c3348e9 Mon Sep 17 00:00:00 2001
From: Ricardo Salveti <44008055+ricardosalveti@users.noreply.github.com>
Date: Wed, 10 Dec 2025 04:55:57 +0900
Subject: [PATCH] boot: handle empty initrd files (#40040)

Commit f8fa4222c9ac3e74e91c64e25e9532c99559cf99 added extra logic to
account for the size of the initrds before allocating the required memory pages,
but missed checking if the initrds were empty before allocating memory.

Extend the initrd options only when the initrd is valid, and add extra
check for validating that there is at least one valid initrd file before
allocating memory, fixing the following crash when booting with empty
initrd files:

src/boot/log.c:30@efi_assert: systemd-boot: Assertion
 'BS->AllocatePages(type, memory_type, n_pages, &addr) == EFI_SUCCESS'
failed at /usr/src/debug/systemd-boot/257.8/src/boot/util.h:95@xmalloc_pages, halting.

Fixes: f8fa4222c9ac3e74e91c64e25e9532c99559cf99
("boot: Make initrd_prepare() semantically equivalent to combine_initrds()")
---
 src/boot/boot.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/boot/boot.c b/src/boot/boot.c
index aa38ff18ee..772edc95a4 100644
--- a/src/boot/boot.c
+++ b/src/boot/boot.c
@@ -2443,12 +2443,6 @@ static EFI_STATUS initrd_prepare(
         size_t size = 0, padded_size = 0;
 
         STRV_FOREACH(i, entry->initrd) {
-                _cleanup_free_ char16_t *o = options;
-                if (o)
-                        options = xasprintf("%ls initrd=%ls", o, *i);
-                else
-                        options = xasprintf("initrd=%ls", *i);
-
                 _cleanup_file_close_ EFI_FILE *handle = NULL;
                 err = root->Open(root, &handle, *i, EFI_FILE_MODE_READ, 0);
                 if (err != EFI_SUCCESS)
@@ -2459,6 +2453,15 @@ static EFI_STATUS initrd_prepare(
                 if (err != EFI_SUCCESS)
                         return err;
 
+                if (info->FileSize == 0) /* Automatically skip over empty files */
+                        continue;
+
+                _cleanup_free_ char16_t *o = options;
+                if (o)
+                        options = xasprintf("%ls initrd=%ls", o, *i);
+                else
+                        options = xasprintf("initrd=%ls", *i);
+
                 size_t inc = info->FileSize;
 
                 if (!INC_SAFE(&padded_size, ALIGN4(inc)))
@@ -2466,6 +2469,14 @@ static EFI_STATUS initrd_prepare(
                 assert_se(INC_SAFE(&size, *(i + 1) ? ALIGN4(inc) : inc));
         }
 
+        /* Skip if no valid initrd files */
+        if (padded_size == 0) {
+                *ret_options = NULL;
+                *ret_initrd_pages = (Pages) {};
+                *ret_initrd_size = 0;
+                return EFI_SUCCESS;
+        }
+
         _cleanup_pages_ Pages pages = xmalloc_initrd_pages(padded_size);
         uint8_t *p = PHYSICAL_ADDRESS_TO_POINTER(pages.addr);