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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=NxwQtp+mIoEoCmpBAjD17aoq2HWLP3++GrG0ABFdOrA=; b=z67PoltlF5fCuVI3jvelk/J5uA8EFcgaseZnCnqxY9MJ3cwmZL2mc5QHhxQwLhYVE4 u0bwvDNnFbd/HvXQ4WaKw494V4t/7CaTjSPW2eEeDtT5EzF5EgCIov93638OEV7+pqKD UODMNwSE8ymsa5Lc/sBUhFP6UXRbZVI4VbHLuNYr1yoIG20wmfI9Q3qSEvh0614Iw9qF PKURYe5CG62AJCO1lNvfNUVlMwpQ7llSbdLujfMbNhRVglcjWGk11Z+4sD352CZwhMHT Dq1FNgMpXB408YFE0zygk62QBzPoR+bhrzA4Ja+F+tFvEg0iuiPp0yshrdb8DsB02BVl 4nlg== X-Gm-Message-State: AFqh2krWM7nH/BonBfheC6ImYBUEvrstQo8rXwZfEdzBxDGfiHVgH/10 C24H0fqlVSskeBbm0UWExICfwQ5MOEjAfRrUr4T7Cw== X-Google-Smtp-Source: AMrXdXvpwM2fYYhnaH4hpGj+cUKmpT4BxVdoiQS9zeBc1ccet5YOeOsvjGtxJep4pMZXaFrmg3ojYV23nCyVkP5eFFA= X-Received: by 2002:a5d:6381:0:b0:285:a49e:b114 with SMTP id p1-20020a5d6381000000b00285a49eb114mr868121wru.246.1672775650517; Tue, 03 Jan 2023 11:54:10 -0800 (PST) MIME-Version: 1.0 References: <20221228194249.170354-1-surenb@google.com> <6ddb468a-3771-92a1-deb1-b07a954293a3@redhat.com> In-Reply-To: <6ddb468a-3771-92a1-deb1-b07a954293a3@redhat.com> From: Suren Baghdasaryan Date: Tue, 3 Jan 2023 11:53:57 -0800 Message-ID: Subject: Re: [PATCH 1/1] mm: fix vma->anon_name memory leak for anonymous shmem VMAs To: David Hildenbrand Cc: akpm@linux-foundation.org, hughd@google.com, hannes@cmpxchg.org, vincent.whitchurch@axis.com, seanjc@google.com, rppt@kernel.org, shy828301@gmail.com, pasha.tatashin@soleen.com, paul.gortmaker@windriver.com, peterx@redhat.com, vbabka@suse.cz, Liam.Howlett@oracle.com, ccross@google.com, willy@infradead.org, arnd@arndb.de, cgel.zte@gmail.com, yuzhao@google.com, bagasdotme@gmail.com, suleiman@google.com, steven@liquorix.net, heftig@archlinux.org, cuigaosheng1@huawei.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, syzbot+91edf9178386a07d06a7@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0CB24180013 X-Stat-Signature: ura1gab79tq5e97pptyxz4abrqf8brpf X-Rspam-User: X-HE-Tag: 1672775651-886883 X-HE-Meta: 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 hEYV0U6S ryIDgGmzZt6CSQkoD+szJ/A9cp6sD4LwtPOx0jWyWfbE6/+cOdhleVAvtDKT32Ar7SJoK1uXsol1Y52tXZIjzVIymjqkgGFFr2JR+80Fv0gjwBMke5Jp4m0peF9f95YmtTmHRHJ3/khmgVh539Pmf0iFWZZ9qWya/xXDE X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jan 2, 2023 at 4:00 AM David Hildenbrand wrote: > > On 28.12.22 20:42, Suren Baghdasaryan wrote: > > free_anon_vma_name() is missing a check for anonymous shmem VMA which > > leads to a memory leak due to refcount not being dropped. Fix this by > > adding the missing check. > > > > Fixes: d09e8ca6cb93 ("mm: anonymous shared memory naming") > > Reported-by: syzbot+91edf9178386a07d06a7@syzkaller.appspotmail.com > > Signed-off-by: Suren Baghdasaryan > > --- > > include/linux/mm_inline.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h > > index e8ed225d8f7c..d650ca2c5d29 100644 > > --- a/include/linux/mm_inline.h > > +++ b/include/linux/mm_inline.h > > @@ -413,7 +413,7 @@ static inline void free_anon_vma_name(struct vm_area_struct *vma) > > * Not using anon_vma_name because it generates a warning if mmap_lock > > * is not held, which might be the case here. > > */ > > - if (!vma->vm_file) > > + if (!vma->vm_file || vma_is_anon_shmem(vma)) > > anon_vma_name_put(vma->anon_name); > > Wouldn't it be me more consistent to check for "vma->anon_name"? > > That's what dup_anon_vma_name() checks. And it's safe now because > anon_name is no longer overloaded in vm_area_struct. Thanks for the suggestion, David. Yes, with the recent change that does not overload anon_name, checking for "vma->anon_name" would be simpler. I think we can also drop anon_vma_name() function now (https://elixir.bootlin.com/linux/v6.2-rc2/source/mm/madvise.c#L94) since vma->anon_name does not depend on vma->vm_file anymore, remove the last part of this comment: https://elixir.bootlin.com/linux/v6.2-rc2/source/include/linux/mm_types.h#L584 and use vma->anon_name directly going forward. If all that sounds good, I'll post a separate patch implementing all these changes. So, for this patch I would suggest keeping it as is because functionally it is correct and will change this check along with other corrections I mentioned above in a separate patch. Does that sound good? - if (!vma->vm_file) + if (!vma->vm_file || vma_is_anon_shmem(vma)) > > -- > Thanks, > > David / dhildenb >