lkml.org 
[lkml]   [2011]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[34-longterm 135/260] aio: check for multiplication overflow in do_io_submit
Date
From: Jeff Moyer <jmoyer@redhat.com>

commit 75e1c70fc31490ef8a373ea2a4bea2524099b478 upstream.

Tavis Ormandy pointed out that do_io_submit does not do proper bounds
checking on the passed-in iocb array:

       if (unlikely(nr < 0))
               return -EINVAL;
       if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(iocbpp)))))
               return -EFAULT;                      ^^^^^^^^^^^^^^^^^^
The attached patch checks for overflow, and if it is detected, the
number of iocbs submitted is scaled down to a number that will fit in
the long.  This is an ok thing to do, as sys_io_submit is documented as
returning the number of iocbs submitted, so callers should handle a
return value of less than the 'nr' argument passed in.

Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/aio.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 48fdeeb..94b6cd6 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1659,6 +1659,9 @@ long do_io_submit(aio_context_t ctx_id, long nr,
if (unlikely(nr < 0))
return -EINVAL;

+ if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
+ nr = LONG_MAX/sizeof(*iocbpp);
+
if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
return -EFAULT;

--
1.7.3.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-01-02 08:31    [from the cache]
©2003-2011 Jasper Spaans