[ovs-dev] [PATCH] flow: Avoid buffer overread in parse_nsh() for malformed packet.

[Ben Pfaff]

Found by libfuzzer.

CC: Jan Scheurich <jan.scheurich at ericsson.com>
Fixes: 7edef47b4896 ("NSH: Minor bugfixes")
Reported-by: Bhargava Shastry <bshastry at sec.t-labs.tu-berlin.de>
Signed-off-by: Ben Pfaff <blp at ovn.org>
---
 lib/flow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/flow.c b/lib/flow.c
index 1adc49970a3a..bc24fe7e20d3 100644
--- a/lib/flow.c
+++ b/lib/flow.c
@@ -553,7 +553,7 @@ parse_nsh(const void **datap, size_t *sizep, struct flow_nsh *key)
     /* NSH header length is in 4 byte words. */
     length = ((ver_flags_len & NSH_LEN_MASK) >> NSH_LEN_SHIFT) << 2;
 
-    if (version != 0) {
+    if (length > *sizep || version != 0) {
         return false;
     }
 
-- 
2.10.2