core_pattern: fix up a few miscellaneous bugs

Fix do_coredump to detect a crash in the user mode helper process and abort
the attempt to recursively dump core to another copy of the helper process,
potentially ad-infinitum.

[akpm@linux-foundation.org: cleanups]
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Cc: <martin.pitt@ubuntu.com>
Cc: <wwoods@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 2 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 6450157062ea..cbd183daaad4 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1762,14 +1762,27 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
                 goto fail_unlock;
 
         if (ispipe) {
-                core_limit = RLIM_INFINITY;
                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
                 /* Terminate the string before the first option */
                 delimit = strchr(corename, ' ');
                 if (delimit)
                         *delimit = '\0';
+                delimit = strrchr(helper_argv[0], '/');
+                if (delimit)
+                        delimit++;
+                else
+                        delimit = helper_argv[0];
+                if (!strcmp(delimit, current->comm)) {
+                        printk(KERN_NOTICE "Recursive core dump detected, "
+                                        "aborting\n");
+                        goto fail_unlock;
+                }
+
+                core_limit = RLIM_INFINITY;
+
                 /* SIGPIPE can happen, but it's just never processed */
-                if(call_usermodehelper_pipe(corename+1, helper_argv, NULL, &file)) {
+                if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
+                                &file)) {
                         printk(KERN_INFO "Core dump to %s pipe failed\n",
                                corename);
                         goto fail_unlock;