coredump: escape / in hostname and comm

Change every occurence of / in comm and hostname to !.  If the process
changes its name to contain /, the core is not dumped (if the directory
tree doesn't exist like that).  The same with hostname being something
like myhost/3.  Fix this behaviour by using the escape loop used in %E.
(We extract it to a separate function.)

Now both with comm == myprocess/1 and hostname == myhost/1, the core is
dumped like (kernel.core_pattern='core.%p.%e.%h):
core.2349.myprocess!1.myhost!1

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 8 deletions

diff --git a/fs/exec.c b/fs/exec.c
index a682624de572..27d487f913d3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1649,15 +1649,26 @@ expand_fail:
         return ret;
 }
 
+static void cn_escape(char *str)
+{
+        for (; *str; str++)
+                if (*str == '/')
+                        *str = '!';
+}
+
 static int cn_print_exe_file(struct core_name *cn)
 {
         struct file *exe_file;
-        char *pathbuf, *path, *p;
+        char *pathbuf, *path;
         int ret;
 
         exe_file = get_mm_exe_file(current->mm);
-        if (!exe_file)
-                return cn_printf(cn, "%s (path unknown)", current->comm);
+        if (!exe_file) {
+                char *commstart = cn->corename + cn->used;
+                ret = cn_printf(cn, "%s (path unknown)", current->comm);
+                cn_escape(commstart);
+                return ret;
+        }
 
         pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
         if (!pathbuf) {
@@ -1671,9 +1682,7 @@ static int cn_print_exe_file(struct core_name *cn)
                 goto free_buf;
         }
 
-        for (p = path; *p; p++)
-                if (*p == '/')
-                        *p = '!';
+        cn_escape(path);
 
         ret = cn_printf(cn, "%s", path);
 
@@ -1745,16 +1754,22 @@ static int format_corename(struct core_name *cn, long signr)
                                 break;
                         }
                         /* hostname */
-                        case 'h':
+                        case 'h': {
+                                char *namestart = cn->corename + cn->used;
                                 down_read(&uts_sem);
                                 err = cn_printf(cn, "%s",
                                               utsname()->nodename);
                                 up_read(&uts_sem);
+                                cn_escape(namestart);
                                 break;
+                        }
                         /* executable */
-                        case 'e':
+                        case 'e': {
+                                char *commstart = cn->corename + cn->used;
                                 err = cn_printf(cn, "%s", current->comm);
+                                cn_escape(commstart);
                                 break;
+                        }
                         case 'E':
                                 err = cn_print_exe_file(cn);
                                 break;