linux-kernel - [PATCH 32/41] mm: prevent userfaults to be handled under per-vma lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230109205336.3665937-33-surenb@google.com>
Date:   Mon,  9 Jan 2023 12:53:27 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net,
        dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
        peterz@...radead.org, ldufour@...ux.ibm.com,
        laurent.dufour@...ibm.com, paulmck@...nel.org, luto@...nel.org,
        songliubraving@...com, peterx@...hat.com, david@...hat.com,
        dhowells@...hat.com, hughd@...gle.com, bigeasy@...utronix.de,
        kent.overstreet@...ux.dev, punit.agrawal@...edance.com,
        lstoakes@...il.com, peterjung1337@...il.com, rientjes@...gle.com,
        axelrasmussen@...gle.com, joelaf@...gle.com, minchan@...gle.com,
        jannh@...gle.com, shakeelb@...gle.com, tatashin@...gle.com,
        edumazet@...gle.com, gthelen@...gle.com, gurua@...gle.com,
        arjunroy@...gle.com, soheil@...gle.com, hughlynch@...gle.com,
        leewalsh@...gle.com, posk@...gle.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        surenb@...gle.com
Subject: [PATCH 32/41] mm: prevent userfaults to be handled under per-vma lock

Due to the possibility of handle_userfault dropping mmap_lock, avoid fault
handling under VMA lock and retry holding mmap_lock. This can be handled
more gracefully in the future.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
Suggested-by: Peter Xu <peterx@...hat.com>
---
 mm/memory.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 20806bc8b4eb..12508f4d845a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5273,6 +5273,13 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
 	if (!vma->anon_vma)
 		goto inval;
 
+	/*
+	 * Due to the possibility of userfault handler dropping mmap_lock, avoid
+	 * it for now and fall back to page fault handling under mmap_lock.
+	 */
+	if (userfaultfd_armed(vma))
+		goto inval;
+
 	if (!vma_read_trylock(vma))
 		goto inval;
 
-- 
2.39.0