1 files changed, 76 insertions, 38 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 5c833c18d0d..d49be6bc179 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -55,6 +55,7 @@
 #include <linux/kmod.h>
 #include <linux/fsnotify.h>
 #include <linux/fs_struct.h>
+#include <linux/pipe_fs_i.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -63,6 +64,7 @@
 
 int core_uses_pid;
 char core_pattern[CORENAME_MAX_SIZE] = "core";
+unsigned int core_pipe_limit;
 int suid_dumpable = 0;
 
 /* The maximal length of core_pattern is also specified in sysctl.c */
@@ -1393,18 +1395,16 @@ out_ret:
 	return retval;
 }
 
-int set_binfmt(struct linux_binfmt *new)
+void set_binfmt(struct linux_binfmt *new)
 {
-	struct linux_binfmt *old = current->binfmt;
+	struct mm_struct *mm = current->mm;
 
-	if (new) {
-		if (!try_module_get(new->module))
-			return -1;
-	}
-	current->binfmt = new;
-	if (old)
-		module_put(old->module);
-	return 0;
+	if (mm->binfmt)
+		module_put(mm->binfmt->module);
+
+	mm->binfmt = new;
+	if (new)
+		__module_get(new->module);
 }
 
 EXPORT_SYMBOL(set_binfmt);
@@ -1728,6 +1728,29 @@ int get_dumpable(struct mm_struct *mm)
 	return (ret >= 2) ? 2 : ret;
 }
 
+static void wait_for_dump_helpers(struct file *file)
+{
+	struct pipe_inode_info *pipe;
+
+	pipe = file->f_path.dentry->d_inode->i_pipe;
+
+	pipe_lock(pipe);
+	pipe->readers++;
+	pipe->writers--;
+
+	while ((pipe->readers > 1) && (!signal_pending(current))) {
+		wake_up_interruptible_sync(&pipe->wait);
+		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+		pipe_wait(pipe);
+	}
+
+	pipe->readers--;
+	pipe->writers++;
+	pipe_unlock(pipe);
+
+}
+
+
 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
 {
 	struct core_state core_state;
@@ -1744,11 +1767,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
 	unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
 	char **helper_argv = NULL;
 	int helper_argc = 0;
-	char *delimit;
+	int dump_count = 0;
+	static atomic_t core_dump_count = ATOMIC_INIT(0);
 
 	audit_core_dumps(signr);
 
-	binfmt = current->binfmt;
+	binfmt = mm->binfmt;
 	if (!binfmt || !binfmt->core_dump)
 		goto fail;
 
@@ -1799,54 +1823,63 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
  	lock_kernel();
 	ispipe = format_corename(corename, signr);
 	unlock_kernel();
-	/*
-	 * Don't bother to check the RLIMIT_CORE value if core_pattern points
-	 * to a pipe.  Since we're not writing directly to the filesystem
-	 * RLIMIT_CORE doesn't really apply, as no actual core file will be
-	 * created unless the pipe reader choses to write out the core file
-	 * at which point file size limits and permissions will be imposed
-	 * as it does with any other process
-	 */
+
 	if ((!ispipe) && (core_limit < binfmt->min_coredump))
 		goto fail_unlock;
 
  	if (ispipe) {
+		if (core_limit == 0) {
+			/*
+			 * Normally core limits are irrelevant to pipes, since
+			 * we're not writing to the file system, but we use
+			 * core_limit of 0 here as a speacial value. Any
+			 * non-zero limit gets set to RLIM_INFINITY below, but
+			 * a limit of 0 skips the dump.  This is a consistent
+			 * way to catch recursive crashes.  We can still crash
+			 * if the core_pattern binary sets RLIM_CORE =  !0
+			 * but it runs as root, and can do lots of stupid things
+			 * Note that we use task_tgid_vnr here to grab the pid
+			 * of the process group leader.  That way we get the
+			 * right pid if a thread in a multi-threaded
+			 * core_pattern process dies.
+			 */
+			printk(KERN_WARNING
+				"Process %d(%s) has RLIMIT_CORE set to 0\n",
+				task_tgid_vnr(current), current->comm);
+			printk(KERN_WARNING "Aborting core\n");
+			goto fail_unlock;
+		}
+
+		dump_count = atomic_inc_return(&core_dump_count);
+		if (core_pipe_limit && (core_pipe_limit < dump_count)) {
+			printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
+			       task_tgid_vnr(current), current->comm);
+			printk(KERN_WARNING "Skipping core dump\n");
+			goto fail_dropcount;
+		}
+
 		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
 		if (!helper_argv) {
 			printk(KERN_WARNING "%s failed to allocate memory\n",
 			       __func__);
-			goto fail_unlock;
-		}
-		/* 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;
+			goto fail_dropcount;
 		}
 
 		core_limit = RLIM_INFINITY;
 
 		/* SIGPIPE can happen, but it's just never processed */
- 		if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
+		if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
 				&file)) {
  			printk(KERN_INFO "Core dump to %s pipe failed\n",
 			       corename);
- 			goto fail_unlock;
+			goto fail_dropcount;
  		}
  	} else
  		file = filp_open(corename,
 				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
 				 0600);
 	if (IS_ERR(file))
-		goto fail_unlock;
+		goto fail_dropcount;
 	inode = file->f_path.dentry->d_inode;
 	if (inode->i_nlink > 1)
 		goto close_fail;	/* multiple links - don't dump */
@@ -1875,7 +1908,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
 	if (retval)
 		current->signal->group_exit_code |= 0x80;
 close_fail:
+	if (ispipe && core_pipe_limit)
+		wait_for_dump_helpers(file);
 	filp_close(file, NULL);
+fail_dropcount:
+	if (dump_count)
+		atomic_dec(&core_dump_count);
 fail_unlock:
 	if (helper_argv)
 		argv_free(helper_argv);