mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

exec: Move would_dump into flush_old_exec 

commit f87d1c9559 upstream.

I goofed when I added mm->user_ns support to would_dump.  I missed the
fact that in the case of binfmt_loader, binfmt_em86, binfmt_misc, and
binfmt_script bprm->file is reassigned.  Which made the move of
would_dump from setup_new_exec to __do_execve_file before exec_binprm
incorrect as it can result in would_dump running on the script instead
of the interpreter of the script.

The net result is that the code stopped making unreadable interpreters
undumpable.  Which allows them to be ptraced and written to disk
without special permissions.  Oops.

The move was necessary because the call in set_new_exec was after
bprm->mm was no longer valid.

To correct this mistake move the misplaced would_dump from
__do_execve_file into flos_old_exec, before exec_mmap is called.

I tested and confirmed that without this fix I can attach with gdb to
a script with an unreadable interpreter, and with this fix I can not.

Cc: stable@vger.kernel.org
Fixes: f84df2a6f2 ("exec: Ensure mm->user_ns contains the execed files")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric W. Biederman 2020-05-16 16:29:20 -05:00 committed by Greg Kroah-Hartman
parent 0cb155717e
commit c5768e0a14
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/exec.c
View File

@ -1264,6 +1264,8 @@ int flush_old_exec(struct linux_binprm * bprm)
*/
set_mm_exe_file(bprm->mm, bprm->file);
would_dump(bprm, bprm->file);
/*
* Release all of the old mmap stuff
*/
@ -1797,8 +1799,6 @@ static int do_execveat_common(int fd, struct filename *filename,
if (retval < 0)
goto out;
would_dump(bprm, bprm->file);
retval = exec_binprm(bprm);
if (retval < 0)
goto out;