Messages in this thread |  | | | Date | Wed, 7 Mar 2012 11:50:18 -0500 | | From | Benjamin LaHaise <> | | Subject | Re: [PATCH] aio: fix io_setup/io_destroy race |
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On Wed, Mar 07, 2012 at 05:16:35AM +0000, Al Viro wrote: > Have ioctx_alloc() return an extra reference, so that caller would drop it > on success and not bother with re-grabbing it on failure exit. The current > code is obviously broken - io_destroy() from another thread that managed > to guess the address io_setup() would've returned would free ioctx right > under us; gets especially interesting if aio_context_t * we pass to > io_setup() points to PROT_READ mapping, so put_user() fails and we end > up doing io_destroy() on kioctx another thread has just got freed... > Cc: stable@vger.kernel.org > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
The fix looks good, and works with a quick test program checking the two cases involved (ioctx create success + failure due to PROT_READ).
-ben
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