Hello Greg, > -----Original Message----- > From: Greg KH [mailto:gre...@linuxfoundation.org] > Sent: Wednesday, November 06, 2013 4:59 PM > To: Liu, Chuansheng > Cc: dmitry.torok...@gmail.com; t...@kernel.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH] devres: Freeing the drs after all release() are called > > On Wed, Nov 06, 2013 at 02:40:18PM +0800, Chuansheng Liu wrote: > > > > In release_nodes(), it will call dr->node.release() and kfree > > dr one by one. > > > > But sometimes the previous dr maybe be used by next .release(), > > such as: > > [50314.855534] [<c12b172f>] ? synchronize_irq+0x3f/0xb0 > > [50314.861193] [<c12b18e9>] __free_irq+0x149/0x200 > > [50314.866367] [<c12b19e3>] free_irq+0x43/0xa0 > > [50314.871152] [<c12b4864>] devm_irq_release+0x14/0x20 > > [50314.876713] [<c169e806>] release_nodes+0x136/0x1b0 > > [50314.882178] [<c169ee79>] devres_release_all+0x39/0x60 > > [50314.887935] [<c169b411>] __device_release_driver+0x71/0xd0 > > > > the free_irq() will sync the last irq handling, which maybe use > > freed dr, then it will cause memory corruption. > > > > Here split the dr kfreeing actions after all dr->node.release(). > > But you aren't really solving any problems here, how is dr being used > after the release function is called? Who is doing it in such a way > that this change would really fix anything? > The driver code is as below: _INIT() {
A = devm_kzalloc(); B= devm_request_threaded_irq(isr_handler); C = devm_kzalloc(); } When driver _EXIT, the devres_release_all () will be called. The C will be kfreed before B, but when freeing irq B, the pending isr_handler() possibly will access the memory B which has been freed. Then the memory corruption occurred. This patch can solve this scenario. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
