Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1689337

Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or corruption

Show all headers | View raw

On 17.07.2017 20:54, Matthew Wilcox wrote:
> On Mon, Jul 17, 2017 at 07:45:07PM +0300, Alexander Popov wrote:
>> Add an assertion similar to "fasttop" check in GNU C Library allocator:
>> an object added to a singly linked freelist should not point to itself.
>> That helps to detect some double free errors (e.g. CVE-2017-2636) without
>> slub_debug and KASAN. Testing with hackbench doesn't show any noticeable
>> performance penalty.
> 
>>  {
>> +	BUG_ON(object == fp); /* naive detection of double free or corruption */
>>  	*(void **)(object + s->offset) = fp;
>>  }
> 
> Is BUG() the best response to this situation?  If it's a corruption, then
> yes, but if we spot a double-free, then surely we should WARN() and return
> without doing anything?

Hello Matthew,

Double-free leads to the memory corruption too, since the next two kmalloc()
calls return the same address to their callers. And we can spot it early here.

--
Alexander

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 1/1] mm/slub.c: add a naive detection of double free or corruption Alexander Popov <alex.popov@linux.com> - 2017-07-17 18:50 +0200
  Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or  corruption Christopher Lameter <cl@linux.com> - 2017-07-17 19:00 +0200
  Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or  corruption Matthew Wilcox <willy@infradead.org> - 2017-07-17 20:00 +0200
    Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or  corruption Christopher Lameter <cl@linux.com> - 2017-07-17 20:20 +0200
      Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or  corruption Alexander Popov <alex.popov@linux.com> - 2017-07-17 21:10 +0200
        Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or corruption Kees Cook <keescook@chromium.org> - 2017-07-17 21:20 +0200
    Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or  corruption Alexander Popov <alex.popov@linux.com> - 2017-07-17 20:30 +0200

csiph-web