[lxc-devel] [PATCH] fix segfault on lxc-create with bad template name
Serge Hallyn
serge.hallyn at ubuntu.com
Thu Sep 26 13:11:25 UTC 2013
Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> Quoting Dwight Engen (dwight.engen at oracle.com):
> > - change get_template_path() to only return NULL or non-NULL since one of
> > the callers was doing a free(-1) which caused the segfault. Handle the
> > NULL template case in the lxcapi_create() caller.
>
> Hm, some people really do want to run lxc-create without a template
> though. I'm not terribly attached to that idea, but I don't want to
> break it if we can help it - would it solve it to just set tpath = NULL
> right after
> ERROR("bad template: %s\n", t);
> and before the goto out?
D'oh, I see now.
> > - make sure to free(tpath) in the sha1sum_file() failure case
> >
> > Signed-off-by: Dwight Engen <dwight.engen at oracle.com>
Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>
thanks,
-serge
> > ---
> > src/lxc/lxccontainer.c | 45 ++++++++++++++++++++-------------------------
> > 1 file changed, 20 insertions(+), 25 deletions(-)
> >
> > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> > index f5d41b3..d3f5b0d 100644
> > --- a/src/lxc/lxccontainer.c
> > +++ b/src/lxc/lxccontainer.c
> > @@ -713,38 +713,32 @@ static struct bdev *do_bdev_create(struct lxc_container *c, const char *type,
> > /*
> > * Given the '-t' template option to lxc-create, figure out what to
> > * do. If the template is a full executable path, use that. If it
> > - * is something like 'sshd', then return $templatepath/lxc-sshd. If
> > - * no template was passed in, return NULL (this is ok).
> > - * On error return (char *) -1.
> > + * is something like 'sshd', then return $templatepath/lxc-sshd.
> > + * On success return the template, on error return NULL.
> > */
> > -char *get_template_path(const char *t)
> > +static char *get_template_path(const char *t)
> > {
> > int ret, len;
> > char *tpath;
> >
> > - if (!t)
> > - return NULL;
> > -
> > if (t[0] == '/' && access(t, X_OK) == 0) {
> > tpath = strdup(t);
> > - if (!tpath)
> > - return (char *) -1;
> > return tpath;
> > }
> >
> > len = strlen(LXCTEMPLATEDIR) + strlen(t) + strlen("/lxc-") + 1;
> > tpath = malloc(len);
> > if (!tpath)
> > - return (char *) -1;
> > + return NULL;
> > ret = snprintf(tpath, len, "%s/lxc-%s", LXCTEMPLATEDIR, t);
> > if (ret < 0 || ret >= len) {
> > free(tpath);
> > - return (char *) -1;
> > + return NULL;
> > }
> > if (access(tpath, X_OK) < 0) {
> > SYSERROR("bad template: %s\n", t);
> > free(tpath);
> > - return (char *) -1;
> > + return NULL;
> > }
> >
> > return tpath;
> > @@ -917,20 +911,19 @@ bool prepend_lxc_header(char *path, const char *t, char *const argv[])
> >
> > #if HAVE_LIBGNUTLS
> > tpath = get_template_path(t);
> > - if (tpath == (char *) -1) {
> > + if (!tpath) {
> > ERROR("bad template: %s\n", t);
> > goto out_free_contents;
> > }
> >
> > - if (tpath) {
> > - have_tpath = true;
> > - ret = sha1sum_file(tpath, md_value);
> > - if (ret < 0) {
> > - ERROR("Error getting sha1sum of %s", tpath);
> > - goto out_free_contents;
> > - }
> > + have_tpath = true;
> > + ret = sha1sum_file(tpath, md_value);
> > + if (ret < 0) {
> > + ERROR("Error getting sha1sum of %s", tpath);
> > free(tpath);
> > + goto out_free_contents;
> > }
> > + free(tpath);
> > #endif
> >
> > process_lock();
> > @@ -1006,16 +999,18 @@ static bool lxcapi_create(struct lxc_container *c, const char *t,
> > {
> > bool bret = false;
> > pid_t pid;
> > - char *tpath;
> > + char *tpath = NULL;
> > int partial_fd;
> >
> > if (!c)
> > return false;
> >
> > - tpath = get_template_path(t);
> > - if (tpath == (char *) -1) {
> > - ERROR("bad template: %s\n", t);
> > - goto out;
> > + if (t) {
> > + tpath = get_template_path(t);
> > + if (!tpath) {
> > + ERROR("bad template: %s\n", t);
> > + goto out;
> > + }
> > }
> >
> > if (!c->save_config(c, NULL)) {
> > --
> > 1.8.1.4
> >
> >
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