[klibc] [klibc:master] inet: Stricter IPv6 field parsing in inet_pton()

[klibc-bot for Ben Hutchings]

Commit-ID:  7359f104c202a6e36212324cdd5aba7964737e9d
Gitweb:     http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=7359f104c202a6e36212324cdd5aba7964737e9d
Author:     Ben Hutchings <ben at decadent.org.uk>
AuthorDate: Thu, 21 Mar 2024 23:12:47 +0100
Committer:  Ben Hutchings <ben at decadent.org.uk>
CommitDate: Thu, 21 Mar 2024 23:30:45 +0100

[klibc] inet: Stricter IPv6 field parsing in inet_pton()

We currently don't range-check the fields of an IPv6 address, so the
following strings are wrongly accepted:

"10000::"
"::10000"

Since we currently only support hexadecimal fields, implement the
range check by limiting the number of digits to 4.

Signed-off-by: Ben Hutchings <ben at decadent.org.uk>

---
 usr/klibc/inet/inet_pton.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/usr/klibc/inet/inet_pton.c b/usr/klibc/inet/inet_pton.c
index a319506a..19706ce0 100644
--- a/usr/klibc/inet/inet_pton.c
+++ b/usr/klibc/inet/inet_pton.c
@@ -32,7 +32,7 @@ int inet_pton(int af, const char *src, void *dst)
 	case AF_INET6:
 		{
 			struct in6_addr *d = (struct in6_addr *)dst;
-			int colons = 0, dcolons = 0;
+			int colons = 0, dcolons = 0, digits = 0;
 			int i;
 			const char *p;
 
@@ -43,7 +43,9 @@ int inet_pton(int af, const char *src, void *dst)
 					colons++;
 					if (p[1] == ':')
 						dcolons++;
-				} else if (!isxdigit((unsigned char)*p))
+					digits = 0;
+				} else if (!isxdigit((unsigned char)*p)
+					   || ++digits > 4)
 					return 0;	/* Invalid address */
 			}