[tip: efi/urgent] efi/libstub: Avoid returning uninitialized data from setup_graphics()

[tip-bot2 for Heinrich Schuchardt]

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     081d5150845ba3fa49151a2f55d3cc03b0987509
Gitweb:        https://git.kernel.org/tip/081d5150845ba3fa49151a2f55d3cc03b0987509
Author:        Heinrich Schuchardt <xypron.glpk@xxxxxx>
AuthorDate:    Sun, 26 Apr 2020 21:49:46 +02:00
Committer:     Ard Biesheuvel <ardb@xxxxxxxxxx>
CommitterDate: Thu, 30 Apr 2020 23:26:30 +02:00

efi/libstub: Avoid returning uninitialized data from setup_graphics()

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@xxxxxx>
Link: https://lore.kernel.org/r/20200426194946.112768-1-xypron.glpk@xxxxxx
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
 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 99a5cde..48161b1 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;
 }