@matheusbsbs / matheus-bagliano / commits / 820d7650cc

connect: reject ssh hostname that begins with a dash

When commands like "git fetch" talk with ssh://$rest_of_URL/, the code splits $rest_of_URL into components like host, port, etc., and then spawns the underlying "ssh" program by formulating argv[] array that has: - the path to ssh command taken from GIT_SSH_COMMAND, etc. - dashed options like '-batch' (for Tortoise), '-p <port>' as needed. - ssh_host, which is supposed to be the hostname parsed out of $rest_of_URL. - then the command to be run on the other side, e.g. git upload-pack. If the ssh_host ends up getting '-<anything>', the argv[] that is used to spawn the command becomes something like: { "ssh", "-p", "22", "-<anything>", "command", "to", "run", NULL } which obviously is bogus, but depending on the actual value of "<anything>", will make "ssh" parse and use it as an option. Prevent this by forbidding ssh_host that begins with a "-". Noticed-by: Joern Schneeweisz of Recurity Labs Reported-by: Brian at GitLab Signed-off-by: Junio C Hamano <gitster@pobox.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Jul 26, 2017 at 10:24 UTC 820d7650cc670d3e4195aad3a5343158c316e8fa

1 file changed +3

connect.c

@@ -754,6 +754,9 @@ struct child_process *git_connect(int fd[2], const char *url,

754 return NULL;

755 }

756

757 + if (ssh_host[0] == '-')

758 + die("strange hostname '%s' blocked", ssh_host);

759 +

760 ssh = getenv("GIT_SSH_COMMAND");

761 if (!ssh) {

762 const char *base;