[PATCH v2 2/3] ecryptfs: fix tag 11 packet exact-fit size check

[Yichong Chen]

parse_tag_11_packet() rejects a packet when the already-consumed tag and
length bytes plus the packet body exceed the caller supplied maximum
packet size.  The check currently adds one extra byte, even though
*packet_size already includes the tag byte before the length is parsed.

Remove the extra byte so a tag 11 packet that exactly fits the available
buffer is accepted while oversized packets are still rejected.

Fixes: 237fead61998 ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig")
Signed-off-by: Yichong Chen <chenyichong@xxxxxxxxxxxxx>
---
 fs/ecryptfs/keystore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 90c2b80..02b5d77 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -1537,7 +1537,7 @@ parse_tag_11_packet(unsigned char *data, unsigned char *contents,
 	}
 	(*packet_size) += length_size;
 	(*tag_11_contents_size) = (body_size - 14);
-	if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
+	if (unlikely((*packet_size) + body_size > max_packet_size)) {
 		printk(KERN_ERR "Packet size exceeds max\n");
 		rc = -EINVAL;
 		goto out;
-- 
2.51.0