linux-kernel - [PATCH 1/7] efi/libstub: Avoid returning uninitialized data from setup

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Date:   Sun, 17 May 2020 14:57:48 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Benjamin Thiel <b.thiel@...teo.de>,
        Borislav Petkov <bp@...en8.de>, Dave Young <dyoung@...hat.com>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Lenny Szubowicz <lszubowi@...hat.com>,
        linux-acpi@...r.kernel.org, Loic Yhuel <loic.yhuel@...il.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Mike Lothian <mike@...eburn.co.uk>,
        Punit Agrawal <punit1.agrawal@...hiba.co.jp>
Subject: [PATCH 1/7] efi/libstub: Avoid returning uninitialized data from setup_graphics()

From: Heinrich Schuchardt <xypron.glpk@....de>

Currently, setup_graphics() ignores the return value of efi_setup_gop(). As
AllocatePool() does not zero out memory, the screen information table will
contain uninitialized data in this case.

We should free the screen information table if efi_setup_gop() returns an
error code.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
Link: https://lore.kernel.org/r/20200426194946.112768-1-xypron.glpk@gmx.de
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 drivers/firmware/efi/libstub/arm-stub.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 99a5cde7c2d8..48161b1dd098 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -60,7 +60,11 @@ static struct screen_info *setup_graphics(void)
 		si = alloc_screen_info();
 		if (!si)
 			return NULL;
-		efi_setup_gop(si, &gop_proto, size);
+		status = efi_setup_gop(si, &gop_proto, size);
+		if (status != EFI_SUCCESS) {
+			free_screen_info(si);
+			return NULL;
+		}
 	}
 	return si;
 }
-- 
2.17.1