laforge submitted this change.

View Change

smpp34_unpack: bound C_OCTET scan with strnlen()

The C_OCTET macro runs strlen() on the attacker-controlled wire buffer
before any bounds check. SMPP PDUs are decoded straight out of a buffer
sized exactly to the wire command_length with no trailing NUL, so a
C-Octet-String field that runs to the end of the buffer without a
terminator makes strlen() read past the end of the allocation (out of
bounds heap read), and the post-hoc "lenval > left" check runs only
after the over-read has already happened.

Scan with strnlen(aux, left) so the read can never go past the remaining
buffer; if no terminator is found within 'left' bytes, lenval becomes
left + 1 and the existing length check rejects the PDU.

This issue has been assigned the CVE candidate identifier
CAN-2026-2051038.

Change-Id: Ie87b16cad0dbdc8ea8397c1b065b8545f23ac814
---
M src/smpp34_unpack.c
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/smpp34_unpack.c b/src/smpp34_unpack.c
index ec73d35..47d34ba 100644
--- a/src/smpp34_unpack.c
+++ b/src/smpp34_unpack.c
@@ -127,7 +127,7 @@
 
 
 #define C_OCTET( inst, par, size ){\
-    lenval = strlen( (char*) aux ) + 1;\
+	lenval = strnlen((char *)aux, left) + 1;\
     if( lenval > left ){\
         PUTLOG("[len(%s):%d(%s)]", par, lenval, \
                                       "Value length exceed buffer length");\

To view, visit change 42889. To unsubscribe, or for help writing mail filters, visit settings.