[PATCH AUTOSEL 5.10 34/39] udf_get_extendedattr() had no boundary checks.

Sasha Levin
2021-09-06T01:27:41Z

From: Stian Skjelstad <stian.skjelstad@gmail.com>

[ 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>
---
fs/udf/misc.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/udf/misc.c b/fs/udf/misc.c
index eab94527340d..1614d308d0f0 100644
--- a/fs/udf/misc.c
+++ b/fs/udf/misc.c
@@ -173,13 +173,22 @@ 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;
}
}

--
2.30.2