From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Fetishev Subject: [PATCH] proc: #68991 Fix GPF in /proc/$PID/map_files Date: Sat, 8 Mar 2014 05:20:33 +0300 Message-ID: <20140308022033.GC5690@owamsq.epam.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, alexandr_terekhov-uRwfk40T5oI@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org List-Id: containers.vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=68991 The expected logic of proc_map_files_get_link() is either to return 0 and initialize 'path' or return an error and leave 'path' uninitialized. By the time dname_to_vma_addr() returns 0 the corresponding vma may have already be gone. In this case the path is not initialized but the return value is still 0. This results in 'general protection fault' inside d_path(). Steps to reproduce: CONFIG_CHECKPOINT_RESTORE=y fd = open(...); while (1) { mmap(fd, ...); munmap(fd, ...); } ls -la /proc/$PID/map_files Signed-off-by: Artem Fetishev Signed-off-by: Aleksandr Terekhov --- diff --git a/fs/proc/base.c b/fs/proc/base.c index 5150706..b976062 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path) if (rc) goto out_mmput; + rc = -ENOENT; down_read(&mm->mmap_sem); vma = find_exact_vma(mm, vm_start, vm_end); if (vma && vma->vm_file) {