diff mbox series

[OpenWrt-Devel,libubox,16/20] Ensure blob_attr length check does not perform out of bounds reads

Message ID 20191219215836.21773-17-ynezz@true.cz
State Accepted
Delegated to: Petr Štetiar
Headers show
Series tests, fuzzing, fixes and improvements | expand

Commit Message

Petr Štetiar Dec. 19, 2019, 9:58 p.m. UTC 
From: Tobias Schramm <tobleminer@gmail.com>

Before there might have been as little as one single byte left which
would result in 3 bytes of blob_attr->id_len being out of bounds.

Acked-by: Yousong Zhou <yszhou4tech@gmail.com>
Signed-off-by: Tobias Schramm <tobleminer@gmail.com>
[line wrapped < 72 chars]
Signed-off-by: Petr Štetiar <ynezz@true.cz>
---
 blob.h    | 4 ++--
 blobmsg.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/blob.h b/blob.h
index af033607e309..6d618767b91a 100644
--- a/blob.h
+++ b/blob.h
@@ -243,7 +243,7 @@  blob_put_u64(struct blob_buf *buf, int id, uint64_t val)
 
 #define __blob_for_each_attr(pos, attr, rem) \
 	for (pos = (struct blob_attr *) attr; \
-	     rem > 0 && (blob_pad_len(pos) <= rem) && \
+	     rem >= sizeof(struct blob_attr) && (blob_pad_len(pos) <= rem) && \
 	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
 	     rem -= blob_pad_len(pos), pos = blob_next(pos))
 
@@ -251,7 +251,7 @@  blob_put_u64(struct blob_buf *buf, int id, uint64_t val)
 #define blob_for_each_attr(pos, attr, rem) \
 	for (rem = attr ? blob_len(attr) : 0, \
 	     pos = (struct blob_attr *) (attr ? blob_data(attr) : NULL); \
-	     rem > 0 && (blob_pad_len(pos) <= rem) && \
+	     rem >= sizeof(struct blob_attr) && (blob_pad_len(pos) <= rem) && \
 	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
 	     rem -= blob_pad_len(pos), pos = blob_next(pos))
 
diff --git a/blobmsg.h b/blobmsg.h
index 0af087890000..00e0fdc1d5c6 100644
--- a/blobmsg.h
+++ b/blobmsg.h
@@ -266,7 +266,7 @@  int blobmsg_printf(struct blob_buf *buf, const char *name, const char *format, .
 #define blobmsg_for_each_attr(pos, attr, rem) \
 	for (rem = attr ? blobmsg_data_len(attr) : 0, \
 	     pos = (struct blob_attr *) (attr ? blobmsg_data(attr) : NULL); \
-	     rem > 0 && (blob_pad_len(pos) <= rem) && \
+	     rem >= sizeof(struct blob_attr) && (blob_pad_len(pos) <= rem) && \
 	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
 	     rem -= blob_pad_len(pos), pos = blob_next(pos))