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Wed, 27 Apr 2022 13:51:17 -0700 From: Tong Zhang To: Paolo Bonzini , Peter Xu , "David Hildenbrand" , =?iso-8859-1?q?Philippe_Mathieu-Dau?= =?iso-8859-1?q?d=E9?= , "qemu-devel@nongnu.org" Subject: [RESEND PATCH] hw/dma: fix crash caused by race condition Thread-Topic: [RESEND PATCH] hw/dma: fix crash caused by race condition Thread-Index: AQHYWniKypkF9nYUvE6RL9M74aeBpw== Date: Wed, 27 Apr 2022 20:51:17 +0000 Message-ID: <20220427205056.2522-1-t.zhang2@samsung.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [105.128.2.176] MIME-Version: 1.0 X-CFilter-Loop: Reflected X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprCKsWRmVeSWpSXmKPExsWy7djX87rH1mQmGbSstrL4uv4Xs8WJTQeZ LfZv+8dqsWX/N3aL4707WCxOvjrP5sDmceDFQnaPnbPusns8ubaZyeP9vqtsASxRXDYpqTmZ ZalF+nYJXBlzv2QVbOasWLiEr4HxJnsXIweHhICJxJx+4y5GTg4hgZWMEj97OLoYuYDsViaJ x8tPsIAkQGpOP1/PCJFYyyjx4dl0KOcjo8TGUwuZIZxljBKdTyYwg7SwCahL/OpcxAaSEBF4 yCjxum8FG0iCWaBeYsrPLUwgtrCAk8T6uS1gtoiAu8SdY++gbD2JnqV7wepZBFQlzs6cwA5i 8wpYSDy71QhmMwqISXw/tYYJYqa4xK0n85kgbhWUWDR7DzOELSbxb9dDNghbUeL+95fsEPV6 EjemToG6R1ti2cLXzBDzBSVOznwC9bOkxMEVN6DsmRwSXc/rIGwXiV8LP0DNlJb4e3cZ1N56 iZm3foCDRUKgh1FizZH17BAJa4lfR/dALeaT+PvrESMk4HklOtqEJjAqzULywiwk581Cct4s JOctYGRZxSheWlycm55abJSXWq5XnJhbXJqXrpecn7uJEZhwTv87nL+D8fqtj3qHGJk4GA8x SnAwK4nwftmdkSTEm5JYWZValB9fVJqTWnyIUZqDRUmcd1nmhkQhgfTEktTs1NSC1CKYLBMH p1QDk638aZOojjCpue4tWkmTmPOqp588ct79Fs+60+ki3tKSx+4eW84UlD7No8IyyvjFyq/T tpyrKWoJtnufrnJg0k1ulRQf3naH+lKDl7Vvj/1/EvtH4EXnv6gfuuv9I7+fXPCYuWtm+grH VR4bFbWe/op9M9380s4t/zOiNS/mrNqdzl69ft3r2lXv5oT5Kfeuz3tieHXnrPevy163sdpx 3P3YJHZF/orQYvFZNa2vJ55lzJ7nYXRo/7tjbvO05NacPveFrezjySRbSwXxwJgzlj7LN+z+ 9v+VsY9X/ZSw1ux/jzVOKa4Xjc595fYn0f+G848tS0+UP3rhIL7Wek24bcauuSw6W07+LQr5 4uvxT1GJpTgj0VCLuag4EQDeQAXapwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprAIsWRmVeSWpSXmKPExsWS2cA0UffYmswkgw3L1Cy+rv/FbHFi00Fm i/3b/rFabNn/jd3ieO8OFouTr86zObB5HHixkN1j56y77B5Prm1m8ni/7ypbAEsUl01Kak5m WWqRvl0CV8bcL1kFmzkrFi7ha2C8yd7FyMkhIWAicfr5esYuRi4OIYHVjBIH/yxig3A+Mkrs Ov8NKrOMUWL6lj3MIC1sAuoSvzohqkQE7jNKPNo9FSzBLFAvMeXnFiYQW1jASWL93BYwW0TA XeLOsXdQtp5Ez9K9bCA2i4CqxNmZE8Du4BWwkHh2qxHMZhQQk/h+ag0TxExxiVtP5jNB3Cog sWTPeWYIW1Ti5eN/rBC2osT97y/ZIer1JG5MncIGYWtLLFv4mhlivqDEyZlPWCDqJSUOrrjB MoFRdBaSFbOQtM9C0j4LSfsCRpZVjOKlxcW56RXFRnmp5XrFibnFpXnpesn5uZsYgZF2+t/h 6B2Mt2991DvEyMTBeIhRgoNZSYT3y+6MJCHelMTKqtSi/Pii0pzU4kOM0hwsSuK8L6MmxgsJ pCeWpGanphakFsFkmTg4pRqYPL7c8p3Hn5X0yENUqPh4YNKOEwm80zRv3z6xJmH5Tvej9k3l oSt3h5fVnfvW7/eCQ1E38bl/+rrUSuGbVwyPsR12WLaJXzrtsfDDcq3/fRMDlZwrtZ5Mmc19 lFvytKfKJmG1P2emvO3Vu9P1iqPHM8v3iU/ZKrX46A+cqUu3Lr4VIPL65pkLK1/x/Utb92hi Wg3fyTuMk7u/v/tvvmxvnfthmYnP3Mq9m3y2CWxckpCbn7ImxOzsRwbjw/9upai1Nk+PnemS 53fl8aaMjS/Kbuyz4bTmZVguFrn5rvpy9wb2+sjZ6X/abWV9TTP8f+Zza6q1t8/xiz22yHNH WJpT1OIHLxl/RvK5G7EvkDdQYinOSDTUYi4qTgQA6PPzISMDAAA= X-CMS-MailID: 20220427205118uscas1p25031437c0cdd4363c104be13033f366a CMS-TYPE: 301P X-CMS-RootMailID: 20220427205118uscas1p25031437c0cdd4363c104be13033f366a References: Received-SPF: pass client-ip=211.189.100.12; envelope-from=t.zhang2@samsung.com; helo=mailout2.w2.samsung.com X-Spam_score_int: -71 X-Spam_score: -7.2 X-Spam_bar: ------- X-Spam_report: (-7.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "ztong0001@gmail.com" , Francisco Londono , Tong Zhang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" assert(dbs->acb) is meant to check the return value of io_func per documented in commit 6bee44ea34 ("dma: the passed io_func does not return NULL"). However, there is a chance that after calling aio_context_release(dbs->ctx); the dma_blk_cb function is called before the assertion and dbs->acb is set to NULL again at line 121. Thus when we run assert at line 181 it will fail. softmmu/dma-helpers.c:181: dma_blk_cb: Assertion `dbs->acb' failed. Reported-by: Francisco Londono Signed-off-by: Tong Zhang --- softmmu/dma-helpers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/softmmu/dma-helpers.c b/softmmu/dma-helpers.c index 7820fec54c..cb81017928 100644 --- a/softmmu/dma-helpers.c +++ b/softmmu/dma-helpers.c @@ -177,8 +177,8 @@ static void dma_blk_cb(void *opaque, int ret) aio_context_acquire(dbs->ctx); dbs->acb = dbs->io_func(dbs->offset, &dbs->iov, dma_blk_cb, dbs, dbs->io_func_opaque); - aio_context_release(dbs->ctx); assert(dbs->acb); + aio_context_release(dbs->ctx); } static void dma_aio_cancel(BlockAIOCB *acb)