fix erroneous return of partial username matches by getspnam[_r]

when using /etc/shadow (rather than tcb) as its backend, getspnam_r
matched any username starting with the caller-provided string rather
than requiring an exact match. in practice this seems to have affected
only systems where one valid username is a prefix for another valid
username, and where the longer username appears first in the shadow
file.

diff --git a/src/passwd/getspnam_r.c b/src/passwd/getspnam_r.c
index 15f8c87..9233952 100644 (file)
--- a/src/passwd/getspnam_r.c
+++ b/src/passwd/getspnam_r.c
@@ -98,7 +98,7 @@ int getspnam_r(const char *name, struct spwd *sp, char *buf, size_t size, struct
 
        pthread_cleanup_push(cleanup, f);
        while (fgets(buf, size, f) && (k=strlen(buf))>0) {
-               if (skip || strncmp(name, buf, l)) {
+               if (skip || strncmp(name, buf, l) || buf[l]!=':') {
                        skip = buf[k-1] != '\n';
                        continue;
                }