From 552a2de0642bb95dd38fcdb7894ea7e07171975e Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Mon, 15 Jul 2024 11:43:07 +0800 Subject: [PATCH] bli: Fix crash in get_part_uuid The get_part_uuid() function made an assumption that the target grub device is a partition device and accessed device->disk->partition without checking for NULL. There are four situations where this assumption is problematic: 1. The device is a net device instead of a disk. 2. The device is an abstraction device, like LVM, RAID, or CRYPTO, which is mostly logical "disk" ((lvmid/) and so on). 3. Firmware RAID may present the ESP to grub as an EFI disk (hd0) device if it is contained within a Linux software RAID. 4. When booting from a cdrom, the ESP is a vfat image indexed by the El Torito boot catalog. The boot device is set to (cd0), corresponding to the cdrom image mounted as an iso9660 filesystem. As a result, get_part_uuid() could lead to a NULL pointer dereference and trigger a synchronous exception during boot if the ESP falls into one of these categories. This patch fixes the problem by adding the necessary checks to handle cases where the ESP is not a partition device. Additionally, to avoid disrupting the boot process, this patch relaxes the severity of the errors in this context to non-critical. Errors will be logged, but they will not prevent the boot process from continuing. Fixes: e0fa7dc84 (bli: Add a module for the Boot Loader Interface) Signed-off-by: Michael Chang Reviewed-By: Oliver Steffen --- grub-core/commands/bli.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/grub-core/commands/bli.c b/grub-core/commands/bli.c index e0d8a54f7..298c5f70a 100644 --- a/grub-core/commands/bli.c +++ b/grub-core/commands/bli.c @@ -48,6 +48,22 @@ get_part_uuid (const char *device_name, char **part_uuid) if (device == NULL) return grub_error (grub_errno, N_("cannot open device: %s"), device_name); + if (device->disk == NULL) + { + grub_dprintf ("bli", "%s is not a disk device, partuuid skipped\n", device_name); + *part_uuid = NULL; + grub_device_close (device); + return GRUB_ERR_NONE; + } + + if (device->disk->partition == NULL) + { + grub_dprintf ("bli", "%s has no partition, partuuid skipped\n", device_name); + *part_uuid = NULL; + grub_device_close (device); + return GRUB_ERR_NONE; + } + disk = grub_disk_open (device->disk->name); if (disk == NULL) { @@ -99,7 +115,7 @@ set_loader_device_part_uuid (void) status = get_part_uuid (device_name, &part_uuid); - if (status == GRUB_ERR_NONE) + if (status == GRUB_ERR_NONE && part_uuid) status = grub_efi_set_variable_to_string ("LoaderDevicePartUUID", &bli_vendor_guid, part_uuid, GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS | GRUB_EFI_VARIABLE_RUNTIME_ACCESS); @@ -117,4 +133,6 @@ GRUB_MOD_INIT (bli) GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS | GRUB_EFI_VARIABLE_RUNTIME_ACCESS); set_loader_device_part_uuid (); + /* No error here is critical, other than being logged */ + grub_print_error (); } -- 2.46.0