keyctl: Fix command table searching

In the keyctl program, when searching the command table, don't trust that an
overlong argument name won't cause memcpy() to segfault.  This is unlikely to
be a problem as any efficient memcpy() is going to start scanning from the
lowest address, given that it has to report on the lowest-addressed difference
if there is one.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/keyctl.c b/keyctl.c
index 7504476..7e5ce6f 100644
--- a/keyctl.c
+++ b/keyctl.c
@@ -155,6 +155,8 @@ int main(int argc, char *argv[])
 	for (cmd = commands; cmd->name; cmd++) {
 		if (!cmd->action)
 			continue;
+		if (strlen(cmd->name) > n)
+			continue;
 		if (memcmp(cmd->name, *argv, n) != 0)
 			continue;