We can patch it for you wholesale

…but remembering costs extra.

Every once in a while, I come across a patch someone sent me, or which I developed in response to a bug report I received, but it’s been weeks or months and I can’t for the life of me remember where it came from, or what it’s for.

Case in point—I’m typing this on a laptop I haven’t used in over two months, and one of the first things I found when I powered it on and opened Chrome was a tab with the following patch:

diff --git a/lib/libpam/modules/pam_login_access/pam_login_access.c b/lib/libpam/modules/pam_login_access/pam_login_access.c
index 945d5eb..b365aee 100644
--- a/lib/libpam/modules/pam_login_access/pam_login_access.c
+++ b/lib/libpam/modules/pam_login_access/pam_login_access.c
@@ -79,20 +79,23 @@ pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused,

        gethostname(hostname, sizeof hostname);

-       if (rhost == NULL || *(const char *)rhost == '\0') {
+       if (tty != NULL && *(const char *)tty != '\0') {
                PAM_LOG("Checking login.access for user %s on tty %s",
                    (const char *)user, (const char *)tty);
                if (login_access(user, tty) != 0)
                        return (PAM_SUCCESS);
                PAM_VERBOSE_ERROR("%s is not allowed to log in on %s",
                    user, tty);
-       } else {
+       } else if (rhost != NULL && *(const char *)rhost != '\0') {
                PAM_LOG("Checking login.access for user %s from host %s",
                    (const char *)user, (const char *)rhost);
                if (login_access(user, rhost) != 0)
                        return (PAM_SUCCESS);
                PAM_VERBOSE_ERROR("%s is not allowed to log in from %s",
                    user, rhost);
+       } else {
+               PAM_VERBOSE_ERROR("neither host nor tty is set");
+               return (PAM_SUCCESS);
        }

        return (PAM_AUTH_ERR);

The patch fixes a long-standing bug in pam_login_access(8) (the code assumes that either PAM_TTY or PAM_RHOST is defined, and crashes if they are both NULL), but I only have the vaguest recollection of the conversation that led up to it. If you’re the author, please contact me so I can give proper credit when I commit it.

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