From nobody Thu Jul 20 16:32:31 2023 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4R6JBW0C1Cz4p2cS; Thu, 20 Jul 2023 16:32:35 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Received: from omta002.cacentral1.a.cloudfilter.net (omta002.cacentral1.a.cloudfilter.net [3.97.99.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "Client", Issuer "CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4R6JBV59qfz4Sjf; Thu, 20 Jul 2023 16:32:34 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Authentication-Results: mx1.freebsd.org; none Received: from shw-obgw-4003a.ext.cloudfilter.net ([10.228.9.183]) by cmsmtp with ESMTP id MSWbqYx0t6NwhMWZtqRVR6; Thu, 20 Jul 2023 16:32:33 +0000 Received: from spqr.komquats.com ([70.66.152.170]) by cmsmtp with ESMTPA id MWZsqoyTrcyvuMWZsqaCWh; Thu, 20 Jul 2023 16:32:33 +0000 X-Authority-Analysis: v=2.4 cv=VbHkgXl9 c=1 sm=1 tr=0 ts=64b961a1 a=y8EK/9tc/U6QY+pUhnbtgQ==:117 a=y8EK/9tc/U6QY+pUhnbtgQ==:17 a=kj9zAlcOel0A:10 a=ws7JD89P4LkA:10 a=6I5d2MoRAAAA:8 a=YxBL1-UpAAAA:8 a=EkcXrb_YAAAA:8 a=AgNmJdvoGADqlrMAvFoA:9 a=CjuIK1q_8ugA:10 a=IjZwj45LgO3ly-622nXo:22 a=Ia-lj3WSrqcvXOmTRaiG:22 a=LK5xJRSDVpKd5WXXoEvA:22 Received: from slippy.cwsent.com (slippy [10.1.1.91]) by spqr.komquats.com (Postfix) with ESMTP id BD0831F4; Thu, 20 Jul 2023 09:32:31 -0700 (PDT) Received: by slippy.cwsent.com (Postfix, from userid 1000) id B1D4277; Thu, 20 Jul 2023 09:32:31 -0700 (PDT) X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.8+dev Reply-to: Cy Schubert From: Cy Schubert X-os: FreeBSD X-Sender: cy@cwsent.com X-URL: http://www.cschubert.com/ To: Konstantin Belousov cc: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: Re: git: 21e45c30c35c - main - mmap(MAP_STACK): on stack grow, use original protection In-reply-to: <202307201412.36KECDSU084918@gitrepo.freebsd.org> References: <202307201412.36KECDSU084918@gitrepo.freebsd.org> Comments: In-reply-to Konstantin Belousov message dated "Thu, 20 Jul 2023 14:12:13 +0000." List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Thu, 20 Jul 2023 09:32:31 -0700 Message-Id: <20230720163231.B1D4277@slippy.cwsent.com> X-CMAE-Envelope: MS4xfCyzJH2+ea3LaynOo/eHGeChIdKRBnjqQ/RuZnsNlgd8pHX0uUbtqrzXkBodnTB5ad6glSyq1ME4iPQNNataUzJxvowp2+t9dtzBhqEyGXG5juwAXjzy d859/2FX5Ibj/jmCKbqTC8i0eHClRWtS8z0Ji/vevcmxeK4dBrEj0k5FHu7MfI8iSMCUkU7+issw2bAOhRWF1fWYTBT9WRYMSz3jubysGB93yXse5vqD8mZ3 WU1jhf3gtCvHczqS/sOI2yIxTK9bFIxqgc9nL+QxvzfLdxKTupxNm/yqdGIlUIX9z/csCCHxRcOcQ3yq6zeaZzfMehxjEcSdkXUCE3dZkd4= X-Rspamd-Queue-Id: 4R6JBV59qfz4Sjf X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:16509, ipnet:3.96.0.0/15, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated In message <202307201412.36KECDSU084918@gitrepo.freebsd.org>, Konstantin Belous ov writes: > The branch main has been updated by kib: > > URL: https://cgit.FreeBSD.org/src/commit/?id=21e45c30c35c9aa732073f725924caf5 > 81c93460 > > commit 21e45c30c35c9aa732073f725924caf581c93460 > Author: Konstantin Belousov > AuthorDate: 2023-07-19 11:05:32 +0000 > Commit: Konstantin Belousov > CommitDate: 2023-07-20 14:11:42 +0000 > > mmap(MAP_STACK): on stack grow, use original protection > > If mprotect(2) changed protection in the bottom of the currently grown > stack region, currently the changed protection would be used for the > stack grow on next fault. This is arguably unexpected. > > Store the original protection for the entry at mmap(2) time in the > offset member of the gap vm_map_entry, and use it for protection of the > grown stack region. > > PR: 272585 > Reported by: John F. Carr > Reviewed by: alc, markj > Sponsored by: The FreeBSD Foundation > MFC after: 1 week > Differential revision: https://reviews.freebsd.org/D41089 > --- > sys/vm/vm_map.c | 24 ++++++++++++++++-------- > sys/vm/vm_map.h | 4 ++++ > 2 files changed, 20 insertions(+), 8 deletions(-) > > diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c > index a02107b5e64d..997a49111a59 100644 > --- a/sys/vm/vm_map.c > +++ b/sys/vm/vm_map.c > @@ -4493,7 +4493,7 @@ static int > vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize, > vm_size_t growsize, vm_prot_t prot, vm_prot_t max, int cow) > { > - vm_map_entry_t new_entry, prev_entry; > + vm_map_entry_t gap_entry, new_entry, prev_entry; > vm_offset_t bot, gap_bot, gap_top, top; > vm_size_t init_ssize, sgp; > int orient, rv; > @@ -4575,11 +4575,14 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos > , vm_size_t max_ssize, > * read-ahead logic is never used for it. Re-use > * next_read of the gap entry to store > * stack_guard_page for vm_map_growstack(). > + * Similarly, since a gap cannot have a backing object, > + * store the original stack protections in the > + * object offset. > */ > - if (orient == MAP_STACK_GROWS_DOWN) > - vm_map_entry_pred(new_entry)->next_read = sgp; > - else > - vm_map_entry_succ(new_entry)->next_read = sgp; > + gap_entry = orient == MAP_STACK_GROWS_DOWN ? > + vm_map_entry_pred(new_entry) : vm_map_entry_succ(new_entry) > ; > + gap_entry->next_read = sgp; > + gap_entry->offset = prot; > } else { > (void)vm_map_delete(map, bot, top); > } > @@ -4599,6 +4602,7 @@ vm_map_growstack(vm_map_t map, vm_offset_t addr, vm_map > _entry_t gap_entry) > struct ucred *cred; > vm_offset_t gap_end, gap_start, grow_start; > vm_size_t grow_amount, guard, max_grow; > + vm_prot_t prot; > rlim_t lmemlim, stacklim, vmemlim; > int rv, rv1 __diagused; > bool gap_deleted, grow_down, is_procstack; > @@ -4739,6 +4743,12 @@ retry: > } > > if (grow_down) { > + /* > + * The gap_entry "offset" field is overloaded. See > + * vm_map_stack_locked(). > + */ > + prot = gap_entry->offset; > + > grow_start = gap_entry->end - grow_amount; > if (gap_entry->start + grow_amount == gap_entry->end) { > gap_start = gap_entry->start; > @@ -4751,9 +4761,7 @@ retry: > gap_deleted = false; > } > rv = vm_map_insert(map, NULL, 0, grow_start, > - grow_start + grow_amount, > - stack_entry->protection, stack_entry->max_protection, > - MAP_STACK_GROWS_DOWN); > + grow_start + grow_amount, prot, prot, MAP_STACK_GROWS_DOWN) > ; > if (rv != KERN_SUCCESS) { > if (gap_deleted) { > rv1 = vm_map_insert(map, NULL, 0, gap_start, > diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h > index fd8b606e8ddc..c4ed36ce57ba 100644 > --- a/sys/vm/vm_map.h > +++ b/sys/vm/vm_map.h > @@ -97,6 +97,10 @@ union vm_map_object { > * a VM object (or sharing map) and offset into that object, > * and user-exported inheritance and protection information. > * Also included is control information for virtual copy operations. > + * > + * For stack gap map entries (MAP_ENTRY_GUARD | MAP_ENTRY_GROWS_DOWN > + * or UP), the next_read member is reused as the stack_guard_page > + * storage, and offset is the stack protection. > */ > struct vm_map_entry { > struct vm_map_entry *left; /* left child or previous entry */ > This commit has caused screen (sysutils/screen) to display the following error when opening a new screen window (ctrl-A c): pid 28473 comm screen-4.9.0 has trashed its stack, killing -- Cheers, Cy Schubert FreeBSD UNIX: Web: https://FreeBSD.org NTP: Web: https://nwtime.org e^(i*pi)+1=0