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From: Ard Biesheuvel <>
Cc: Ard Biesheuvel <>,
	Scott Talbert <>
Subject: [PATCH] efi: don't iterate over EFI vars pointlessly if no SSDT override was specified
Date: Thu, 12 Sep 2019 00:32:39 +0100
Message-ID: <> (raw)

The kernel command line option efivar_ssdt= allows a EFI variable name
to be specified which contains an ACPI SSDT table that will be loaded
into memory by the OS.

Currently, that code will always iterate over the EFI variables and
compare each name with the provided name, even if the command line
option wasn't set to begin with.

So bail early when no variable name was provided.

Cc: Scott Talbert <>
Signed-off-by: Ard Biesheuvel <>
 drivers/firmware/efi/efi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index ad3b1f4866b3..8f020827cdd3 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -282,6 +282,9 @@ static __init int efivar_ssdt_load(void)
 	void *data;
 	int ret;
+	if (!efivar_ssdt[0])
+		return 0;
 	ret = efivar_init(efivar_ssdt_iter, &entries, true, &entries);
 	list_for_each_entry_safe(entry, aux, &entries, list) {

             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11 23:32 Ard Biesheuvel [this message]
2019-09-12 19:35 ` Scott Talbert
2019-09-12 20:42   ` Ard Biesheuvel

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