From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oren Laadan Subject: Re: [PATCH/user_cr] pass a valid stack address to clone_with_pids Date: Thu, 03 Sep 2009 16:44:36 -0400 Message-ID: <4AA02AB4.7080703@librato.com> References: <1251846857.23305.5.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1251846857.23305.5.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Nathan Lynch Cc: Linux Containers List-Id: containers.vger.kernel.org Pulled, thanks. Nathan Lynch wrote: > Off-by-one error: the stack address passed to clone/clone_with_pids > must be within the region allocated. (Also, arithmetic on void * is a > gcc extension; change the relevant variables to char *). > > Signed-off-by: Nathan Lynch > --- > mktree.c | 15 ++++++++------- > 1 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/mktree.c b/mktree.c > index 63be82d..2d8d796 100644 > --- a/mktree.c > +++ b/mktree.c > @@ -1367,18 +1367,19 @@ int ckpt_fork_stub(void *data) > static pid_t ckpt_fork_child(struct ckpt_ctx *ctx, struct task *child) > { > struct target_pid_set pid_set; > - void *stack = NULL; > + char *stack_region; > + char *stack_start; > unsigned long flags = SIGCHLD; > pid_t pid = 0; > > ckpt_dbg("forking child vpid %d flags %#x\n", child->pid, child->flags); > > - stack = malloc(PTHREAD_STACK_MIN); > - if (!stack) { > + stack_region = malloc(PTHREAD_STACK_MIN); > + if (!stack_region) { > perror("stack malloc"); > return -1; > } > - stack += PTHREAD_STACK_MIN; > + stack_start = stack_region + PTHREAD_STACK_MIN - 1; > > pid_set.target_pids = &pid; > pid_set.num_pids = 1; > @@ -1406,15 +1407,15 @@ static pid_t ckpt_fork_child(struct ckpt_ctx *ctx, struct task *child) > else > child->real_parent = _getpid(); > > - pid = clone_with_pids(ckpt_fork_stub, stack, flags, &pid_set, child); > + pid = clone_with_pids(ckpt_fork_stub, stack_start, flags, &pid_set, child); > if (pid < 0) { > perror("clone"); > - free(stack - PTHREAD_STACK_MIN); > + free(stack_region); > return -1; > } > > if (!(child->flags & TASK_THREAD)) > - free(stack - PTHREAD_STACK_MIN); > + free(stack_region); > > ckpt_dbg("forked child vpid %d (asked %d)\n", pid, child->pid); > return pid;