From 86ec48882bd0b06268f93033bce9eea168188fae Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Thu, 3 Oct 2024 15:23:22 +0800 Subject: [PATCH] commands/tpm: Skip loopback image measurement The loopback image is configured to function as a disk by being mapped as a block device. Instead of measuring the entire block device we should focus on tracking the individual files accessed from it. For example, we do not directly measure block devices like hd0 disk but the files opened from it. This method is important to avoid running out of memory since loopback images can be very large. Trying to read and measure the whole image at once could cause out of memory errors and disrupt the boot process. Signed-off-by: Michael Chang Reviewed-by: Daniel Kiper --- grub-core/commands/tpm.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/grub-core/commands/tpm.c b/grub-core/commands/tpm.c index 324423ef8..dde74ab83 100644 --- a/grub-core/commands/tpm.c +++ b/grub-core/commands/tpm.c @@ -36,6 +36,16 @@ grub_tpm_verify_init (grub_file_t io, { *context = io->name; *flags |= GRUB_VERIFY_FLAGS_SINGLE_CHUNK; + + /* + * The loopback image is mapped as a disk allowing it to function like + * a block device. However, we measure files read from the block device + * not the device itself. For example, we don't measure block devices like + * hd0 disk directly. This process is crucial to prevent out-of-memory + * errors as loopback images are inherently large. + */ + if ((type & GRUB_FILE_TYPE_MASK) == GRUB_FILE_TYPE_LOOPBACK) + *flags = GRUB_VERIFY_FLAGS_SKIP_VERIFICATION; return GRUB_ERR_NONE; }