From: Carlos Llamas <cmllamas@google.com>
To: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
Pedro Falcato <pfalcato@suse.de>,
kernel-team@android.com, linux-kernel@vger.kernel.org,
"open list:MEMORY MAPPING" <linux-mm@kvack.org>
Subject: Re: [PATCH] mm/mremap: fix regression in vrm->new_addr check
Date: Thu, 28 Aug 2025 04:06:58 +0000 [thread overview]
Message-ID: <aK_V4sOUOIpEhFC-@google.com> (raw)
In-Reply-To: <xpxoxn25fzhahdyvjp2vgmcnek6oot2hhvb5niz3tw7au46eno@cixyid6ywf27>
On Wed, Aug 27, 2025 at 11:43:39PM -0400, Liam R. Howlett wrote:
> * Carlos Llamas <cmllamas@google.com> [250827 23:27]:
> > Commit 3215eaceca87 ("mm/mremap: refactor initial parameter sanity
> > checks") moved the sanity check for vrm->new_addr from mremap_to() to
> > check_mremap_params().
> >
> > However, this caused a regression as vrm->new_addr is now checked even
> > when MREMAP_FIXED and MREMAP_DONTUNMAP flags are not specified. In this
> > case, vrm->new_addr can be garbage and create unexpected failures.
> >
> > Fix this by moving the new_addr check after the vrm_implies_new_addr()
> > guard. This ensures that the new_addr is only checked when the user has
> > specified one explicitly.
> >
> > Fixes: 3215eaceca87 ("mm/mremap: refactor initial parameter sanity checks")
> > Signed-off-by: Carlos Llamas <cmllamas@google.com>
>
> I assume this showed up with clang?
Right.
The specific test that broke on our end was this:
https://android.googlesource.com/platform/bionic/+/HEAD/tests/__cxa_atexit_test.cpp
Although I'm not exactly sure how __cxa_atexit() implementation uses
mremap() underneath.
next prev parent reply other threads:[~2025-08-28 4:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-28 3:26 [PATCH] mm/mremap: fix regression in vrm->new_addr check Carlos Llamas
2025-08-28 3:43 ` Liam R. Howlett
2025-08-28 4:06 ` Carlos Llamas [this message]
2025-08-28 4:16 ` Carlos Llamas
2025-08-28 5:38 ` Lorenzo Stoakes
2025-08-28 14:13 ` Carlos Llamas
2025-08-28 14:21 ` Vlastimil Babka
2025-08-28 14:22 ` Lorenzo Stoakes
2025-08-28 14:29 ` Carlos Llamas
2025-08-28 14:31 ` Vlastimil Babka
2025-08-28 14:26 ` [PATCH v2] " Carlos Llamas
2025-08-28 14:30 ` Vlastimil Babka
2025-08-28 14:34 ` Lorenzo Stoakes
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