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authorAlexey Izbyshev <izbyshev@ispras.ru>2023-02-27 23:18:02 +0300
committerRich Felker <dalias@aerifal.cx>2023-02-28 12:00:55 -0500
commit595416b11dfbc82d40a59d0edd7e3b04ba7a2d6d (patch)
treec0c7ecedfe3f6413f851fff003b7282146ae73ae
parent1a708ece1ad8b924466e81c5fcdf4e22311fd770 (diff)
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getservbyport_r: fix out-of-bounds buffer read
If the buffer passed to getservbyport_r is just enough to store two
pointers after aligning it, getnameinfo is called with buflen == 0
(which means that service name is not needed) and trivially succeeds.
Then, strtol is called on the address just past the buffer end, and
if it doesn't happen to find the port number there, getservbyport_r
spuriously succeeds and returns the same bad address to the caller.

Fix this by ensuring that buflen is at least 1 when passed to
getnameinfo.
-rw-r--r--src/network/getservbyport_r.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/src/network/getservbyport_r.c b/src/network/getservbyport_r.c
index b7f21c6b..d3a22b8c 100644
--- a/src/network/getservbyport_r.c
+++ b/src/network/getservbyport_r.c
@@ -26,7 +26,7 @@ int getservbyport_r(int port, const char *prots,
 	/* Align buffer */
 	i = (uintptr_t)buf & sizeof(char *)-1;
 	if (!i) i = sizeof(char *);
-	if (buflen < 3*sizeof(char *)-i)
+	if (buflen <= 3*sizeof(char *)-i)
 		return ERANGE;
 	buf += sizeof(char *)-i;
 	buflen -= sizeof(char *)-i;