From e79b543156aec759542ca7aa01d727aea548f833 Mon Sep 17 00:00:00 2001

From: Jakub Filak <jfilak@redhat.com>

Date: Wed, 20 May 2015 06:07:15 +0200

Subject: [PATCH] ccpp: do not unlink failed and big user cores

* We might end up deleting an already existing file.

* Kernel does not delete nor truncate core files. Admittedly, kernel

  knows how process's memory is structured, dumps it per logical

  segments and checks whether a next segment can be written.

* 'ulimit -c' does not seem to be a hard limit. Kernel wrote 8192 bytes

  despite $(ulimit -c) == 6.

Related: #1212818

Signed-off-by: Jakub Filak <jfilak@redhat.com>

---

 src/hooks/abrt-hook-ccpp.c | 45 +++++++++++++++++----------------------------

 1 file changed, 17 insertions(+), 28 deletions(-)

diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c

index 0448216..59fcfce 100644

--- a/src/hooks/abrt-hook-ccpp.c

+++ b/src/hooks/abrt-hook-ccpp.c

@@ -117,8 +117,8 @@ static off_t copyfd_sparse(int src_fd, int dst_fd1, int dst_fd2, off_t size2)

 		size2 -= rd;

 		if (size2 < 0)

 			dst_fd2 = -1;

-//TODO: truncate to 0 or even delete the second file

-//(currently we delete the file later)

+// truncate to 0 or even delete the second file?

+// No, kernel does not delete nor truncate core files.

 	}

  out:

@@ -377,13 +377,20 @@ static int open_user_core(uid_t uid, uid_t fsuid, gid_t fsgid, pid_t pid, char *

 user_core_fail:

     if (user_core_fd >= 0)

-    {

         close(user_core_fd);

-        unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);

-    }

     return -1;

 }

+static int close_user_core(int user_core_fd, off_t core_size)

+{

+    if (user_core_fd >= 0 && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0 || core_size < 0))

+    {

+        perror_msg("Error writing '%s' at '%s'", core_basename, user_pwd);

+        return -1;

+    }

+    return 0;

+}

+

 /* Like xopen, but on error, unlocks and deletes dd and user core */

 static int create_or_die(const char *filename, int user_core_fd)

 {

@@ -398,7 +405,7 @@ static int create_or_die(const char *filename, int user_core_fd)

     if (dd)

         dd_delete(dd);

     if (user_core_fd >= 0)

-        unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);

+        close(user_core_fd);

     errno = sv_errno;

     perror_msg_and_die("Can't open '%s'", filename);

@@ -431,19 +438,10 @@ static int create_user_core(int user_core_fd, pid_t pid, off_t ulimit_c)

     if (user_core_fd >= 0)

     {

         off_t core_size = copyfd_size(STDIN_FILENO, user_core_fd, ulimit_c, COPYFD_SPARSE);

-        if (fsync(user_core_fd) != 0 || close(user_core_fd) != 0 || core_size < 0)

-        {

-            /* perror first, otherwise unlink may trash errno */

-            perror_msg("Error writing '%s' at '%s'", core_basename, user_pwd);

-            unlinkat(dirfd(proc_cwd), core_basename, /*only files*/0);

-            goto finito;

-        }

-        if (ulimit_c == 0 || core_size > ulimit_c)

-        {

-            unlinkat(dirfd(proc_cwd), core_basename, /*only files*/0);

+        if (close_user_core(user_core_fd, core_size) != 0)

             goto finito;

-        }

-        log_notice("Saved core dump of pid %lu to %s at '%s' (%llu bytes)", (long)pid, core_basename, user_pwd, (long long)core_size);

+

+        log_notice("Saved core dump of pid %lu to '%s' at '%s' (%llu bytes)", (long)pid, core_basename, user_pwd, (long long)core_size);

     }

     err = 0;

@@ -822,6 +820,7 @@ int main(int argc, char** argv)

              * ls: cannot access core*: No such file or directory <=== BAD

              */

             core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);

+            close_user_core(user_core_fd, core_size);

             if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)

             {

                 unlink(path);

@@ -832,16 +831,6 @@ int main(int argc, char** argv)

                 goto cleanup_and_exit;

             }

-            if (user_core_fd >= 0

-                /* error writing user coredump? */

-             && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0

-                /* user coredump is too big? */

-                || (ulimit_c == 0 /* paranoia */ || core_size > ulimit_c)

-                )

-            ) {

-                /* nuke it (silently) */

-                unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);

-            }

         }

         else

         {

-- 

2.1.0