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Donenfeld" X-Patchwork-Id: 11803359 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 28FDE139F for ; Mon, 28 Sep 2020 10:35:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C7CB521531 for ; Mon, 28 Sep 2020 10:35:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="J5yqMS89" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C7CB521531 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=zx2c4.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CE6A86B005D; Mon, 28 Sep 2020 06:35:23 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C93F06B0062; Mon, 28 Sep 2020 06:35:23 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BAA476B0068; Mon, 28 Sep 2020 06:35:23 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id A53DA6B005D for ; Mon, 28 Sep 2020 06:35:23 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 62E57282D for ; Mon, 28 Sep 2020 10:35:23 +0000 (UTC) X-FDA: 77312113326.01.spade82_5f11c1d27180 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id 383F11004BE5E for ; Mon, 28 Sep 2020 10:35:23 +0000 (UTC) X-Spam-Summary: 1,0,0,3fc383536d5e1e39,d41d8cd98f00b204,jason@zx2c4.com,,RULES_HIT:41:355:379:800:960:973:988:989:1261:1311:1314:1345:1359:1437:1515:1534:1542:1711:1730:1747:1777:1792:2194:2198:2199:2200:2393:2559:2562:2901:3138:3139:3140:3141:3142:3354:3865:3867:3868:3870:3871:3872:4250:4321:4605:5007:6119:6238:6261:6653:7208:7901:7903:7904:8660:8784:9113:9163:9165:10004:10226:11026:11658:11914:12043:12114:12296:12297:12438:12517:12519:12555:12679:12740:12895:12986:13148:13230:13870:13894:14096:14181:14394:14721:21063:21080:21451:21611:21622:21740:21939:30003:30012:30029:30054:30056,0,RBL:192.95.5.64:@zx2c4.com:.lbl8.mailshell.net-62.2.55.100 64.100.201.201;04y8txnx1oxuirjaekmt46mxdisn7yc8454q1tgs863fz9fo8a6wed1bwinh7tu.xamqgeqpsadf3ixt5ka9xxcu7knctkskj8s3kpu8awoun3n4qdmm7s84qbyo5r5.s-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:26,LUA_SUMMARY:none X-HE-Tag: spade82_5f11c1d27180 X-Filterd-Recvd-Size: 4681 Received: from mail.zx2c4.com (mail.zx2c4.com [192.95.5.64]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Mon, 28 Sep 2020 10:35:22 +0000 (UTC) Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTP id ed9f277a; Mon, 28 Sep 2020 10:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=from:to:cc :subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; s=mail; bh=4eS4KVw+eff75q2oQykBpqEjw NI=; b=J5yqMS89hgyMX0QziV8GupKGPwxrxPZdhMy/7aytvT9d+N8JOimRlW8KT wdpl1ZRiMGXCdDolMdjHdNJZlj+UdT8S5Hc+1rm//VJctpRIgNkE1fyDPRhWFpVl GibowlW8lNe84FWuMuKzshEZfNSI+eCtDq8fr2kmXH9rBV8ic7wR18GCh3dXXKf/ rebuZKy2hxmkvZckpi0ZfTpItF41zFPfbyV6dONaXfTkyKlow0c26VvbN94SFiiO i0c/CZiQkTmkD+pBYbJ9zgGCiH+nBTfo1oQAXcatB1v4ICGWxH6LCoLCAEH1iRsk xqmgddiFjrMNaJxO/PytBuXSevMjg== Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 782f82a2 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Mon, 28 Sep 2020 10:03:55 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-mm@kvack.org, peterx@redhat.com, jgg@ziepe.ca Cc: torvalds@linux-foundation.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, chris@chris-wilson.co.uk, akpm@linux-foundation.org, "Jason A. Donenfeld" Subject: [PATCH] mm: do not rely on mm == current->mm in __get_user_pages_locked Date: Mon, 28 Sep 2020 12:35:07 +0200 Message-Id: <20200928103507.2164-1-Jason@zx2c4.com> In-Reply-To: References: MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000419, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: It seems likely this block was pasted from internal_get_user_pages_fast, which is not passed an mm struct and therefore uses current's. But __get_user_pages_locked is passed an explicit mm, and current->mm is not always valid. This was hit when being called from i915, which uses: pin_user_pages_remote-> __get_user_pages_remote-> __gup_longterm_locked-> __get_user_pages_locked Before, this would lead to an OOPS: BUG: kernel NULL pointer dereference, address: 0000000000000064 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP CPU: 10 PID: 1431 Comm: kworker/u33:1 Tainted: P S U O 5.9.0-rc7+ #140 Hardware name: LENOVO 20QTCTO1WW/20QTCTO1WW, BIOS N2OET47W (1.34 ) 08/06/2020 Workqueue: i915-userptr-acquire __i915_gem_userptr_get_pages_worker [i915] RIP: 0010:__get_user_pages_remote+0xd7/0x310 Code: f5 01 00 00 83 7d 00 01 0f 85 ed 01 00 00 f7 c1 00 00 04 00 0f 84 58 01 00 00 65 48 8b 04 25 00 6d 01 00 48 8b 80 40 03 00 00 40 64 01 00 00 00 65 48 8b 04 25 00 6d 01 00 48 c7 44 24 18 00 RSP: 0018:ffff888fdfe47de0 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 00007fe188531000 RCX: 0000000000040001 RDX: 0000000000000001 RSI: 00007fe188531000 RDI: ffff888ff0748f00 RBP: ffff888fdfe47e54 R08: ffff888fedc7d7c8 R09: 0000000000000000 R10: 0000000000000018 R11: fefefefefefefeff R12: ffff888ff0748f00 R13: ffff888fedc7d7c8 R14: ffff888f81fe3a40 R15: 0000000000042003 FS: 0000000000000000(0000) GS:ffff888ffc480000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000064 CR3: 0000000002009003 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __i915_gem_userptr_get_pages_worker+0xc8/0x260 [i915] process_one_work+0x1ca/0x390 worker_thread+0x48/0x3c0 ? rescuer_thread+0x3d0/0x3d0 kthread+0x114/0x130 ? kthread_create_worker_on_cpu+0x40/0x40 ret_from_fork+0x1f/0x30 CR2: 0000000000000064 This commit fixes the problem by using the mm pointer passed to the function rather than the bogus one in current. Fixes: 008cfe4418b3 ("mm: Introduce mm_struct.has_pinned") Cc: Jason Gunthorpe Cc: Peter Xu Signed-off-by: Jason A. Donenfeld Reviewed-by: Jason Gunthorpe Reviewed-by: Peter Xu --- mm/gup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index dfe781d2ad4c..e869c634cc9a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1256,7 +1256,7 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, } if (flags & FOLL_PIN) - atomic_set(¤t->mm->has_pinned, 1); + atomic_set(&mm->has_pinned, 1); /* * FOLL_PIN and FOLL_GET are mutually exclusive. Traditional behavior