From: Stian Skjelstad <stian.skjelstad@gmail.com>
Date: Sun, 22 Aug 2021 09:33:32 +0000 (+0200)
Subject: udf_get_extendedattr() had no boundary checks.
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=703884a1dfb7844c3ba9899132bbab73d2e4240c;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

udf_get_extendedattr() had no boundary checks.

[ Upstream commit 58bc6d1be2f3b0ceecb6027dfa17513ec6aa2abb ]

When parsing the ExtendedAttr data, malicous or corrupt attribute length
could cause kernel hangs and buffer overruns in some special cases.

Link: https://lore.kernel.org/r/20210822093332.25234-1-stian.skjelstad@gmail.com
Signed-off-by: Stian Skjelstad <stian.skjelstad@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/udf/misc.c b/fs/udf/misc.c
index 71d1c25f360d..8c7f9ea251e5 100644
--- a/fs/udf/misc.c
+++ b/fs/udf/misc.c
@@ -175,13 +175,22 @@ struct genericFormat *udf_get_extendedattr(struct inode *inode, uint32_t type,
 		else
 			offset = le32_to_cpu(eahd->appAttrLocation);
 
-		while (offset < iinfo->i_lenEAttr) {
+		while (offset + sizeof(*gaf) < iinfo->i_lenEAttr) {
+			uint32_t attrLength;
+
 			gaf = (struct genericFormat *)&ea[offset];
+			attrLength = le32_to_cpu(gaf->attrLength);
+
+			/* Detect undersized elements and buffer overflows */
+			if ((attrLength < sizeof(*gaf)) ||
+			    (attrLength > (iinfo->i_lenEAttr - offset)))
+				break;
+
 			if (le32_to_cpu(gaf->attrType) == type &&
 					gaf->attrSubtype == subtype)
 				return gaf;
 			else
-				offset += le32_to_cpu(gaf->attrLength);
+				offset += attrLength;
 		}
 	}