linux-kernel - [PATCH 4/5] uprobes: kill copy_vma()->uprobe

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120708203008.GA18236@redhat.com>
Date:	Sun, 8 Jul 2012 22:30:08 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] uprobes: kill copy_vma()->uprobe_mmap()

Kill copy_vma()->uprobe_mmap(new_vma), it is absolutely wrong.

This new_vma was just initialized to represent the new unmapped area,
[vm_start, vm_end) was returned by get_unmapped_area() in the caller.

This means that uprobe_mmap()->get_user_pages() will fail for sure,
simply because find_vma() can never succeed. And I verified that
sys_mremap()->mremap_to() indeed always fails with the wrong ENOMEM
code if [addr, addr+old_len] is probed.

And why this uprobe_mmap() was added? I believe the intent was wrong.
Note that the caller is going to do move_page_tables(), all registered
uprobes are already faulted in, we only change the virtual addresses.

NOTE: However, somehow we need to close the race with uprobe_register()
which relies on map_info->vaddr. This needs another fix I'll try to do
later. Probably we need uprobe_mmap() in move_vma() but we can not do
this right now, this can confuse uprobes_state.counter (which I still
hope we are going to kill).

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 mm/mmap.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 3edfcdf..e5a4614 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2418,9 +2418,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 			if (new_vma->vm_file) {
 				get_file(new_vma->vm_file);

-				if (uprobe_mmap(new_vma))
-					goto out_free_mempol;
-
 				if (vma->vm_flags & VM_EXECUTABLE)
 					added_exe_file_vma(mm);
 			}
-- 
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/