From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Tue, 23 Feb 2021 20:15:35 +0000 (+0100)
Subject: efi_loader: limit output length for VenHw, VenMedia
X-Git-Url: http://git.dujemihanovic.xyz/html/%7B%7B%20%28.OutputFormats.Get?a=commitdiff_plain;h=9c081a7eabd4e5f54bd692df722705bc5ec57891;p=u-boot.git

efi_loader: limit output length for VenHw, VenMedia

VenHw and VenMedia device path nodes may carry vendor defined data of
arbitrary length. When converting a device path node to text ensure that we
do not overrun our internal buffer.

In our implementation of
EFI_DEVICE_PATH_TO_TEXT_PROTOCOL.ConvertDevicePathToText() we could first
determine the output length and then allocate buffers but that would nearly
double the code size. Therefore keep the preallocated buffers and truncate
excessive device paths instead.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---

diff --git a/lib/efi_loader/efi_device_path_to_text.c b/lib/efi_loader/efi_device_path_to_text.c
index 81b8ac23ba..edc9fdc387 100644
--- a/lib/efi_loader/efi_device_path_to_text.c
+++ b/lib/efi_loader/efi_device_path_to_text.c
@@ -67,7 +67,8 @@ static char *dp_hardware(char *s, struct efi_device_path *dp)
 
 		s += sprintf(s, "VenHw(%pUl", &vdp->guid);
 		n = (int)vdp->dp.length - sizeof(struct efi_device_path_vendor);
-		if (n > 0) {
+		/* Node must fit into MAX_NODE_LEN) */
+		if (n > 0 && n < MAX_NODE_LEN / 2 - 22) {
 			s += sprintf(s, ",");
 			for (i = 0; i < n; ++i)
 				s += sprintf(s, "%02x", vdp->vendor_data[i]);
@@ -251,7 +252,8 @@ static char *dp_media(char *s, struct efi_device_path *dp)
 
 		s += sprintf(s, "VenMedia(%pUl", &vdp->guid);
 		n = (int)vdp->dp.length - sizeof(struct efi_device_path_vendor);
-		if (n > 0) {
+		/* Node must fit into MAX_NODE_LEN) */
+		if (n > 0 && n < MAX_NODE_LEN / 2 - 24) {
 			s += sprintf(s, ",");
 			for (i = 0; i < n; ++i)
 				s += sprintf(s, "%02x", vdp->vendor_data[i]);