From: Egbert Eich <eich@suse.com>
Date: Sun Oct 9 08:07:23 2022 +0200
Subject: Make sure info block for external links has at least 3 bytes
Patch-mainline: Not yet
Git-repo: ssh://eich@192.168.122.1:/home/eich/sources/HPC/hdf5
Git-commit: 082bfe392b04b1137da9eabd1ecac76c212ab385
References: 

According to the specification, the information block for external links
contains 1 byte of version/flag information and two 0 terminated strings
for the object linked to and the full path.
Although not very useful, the minimum string length for each would be one
byte.

This fixes CVE-2018-16438.

Signed-off-by: Egbert Eich <eich@suse.com>
Signed-off-by: Egbert Eich <eich@suse.de>
---
 src/H5Olink.c | 2 ++
 1 file changed, 2 insertions(+)
diff --git a/src/H5Olink.c b/src/H5Olink.c
index 51c44a36b0..074744b022 100644
--- a/src/H5Olink.c
+++ b/src/H5Olink.c
@@ -241,6 +241,8 @@ H5O__link_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNUSE
             /* A UD link.  Get the user-supplied data */
             UINT16DECODE(p, len)
             lnk->u.ud.size = len;
+            if (lnk->type == H5L_TYPE_EXTERNAL && len < 3)
+                HGOTO_ERROR(H5E_OHDR, H5E_OVERFLOW, NULL, "external link information lenght < 3")
             if (len > 0) {
                 /* Make sure that length doesn't exceed buffer size, which could
                    occur when the file is corrupted */
