From: Thomas Gleixner <tglx@kernel.org>
To: Andrii Nakryiko <andrii@kernel.org>,
akpm@linux-foundation.org, linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org,
surenb@google.com, shakeel.butt@linux.dev,
Andrii Nakryiko <andrii@kernel.org>,
syzbot+4e70c8e0a2017b432f7a@syzkaller.appspotmail.com,
syzbot+237b5b985b78c1da9600@syzkaller.appspotmail.com,
Peter Zijlstra <peterz@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [BUG] [PATCH v2 mm-stable] procfs: avoid fetching build ID while holding VMA lock
Date: Tue, 10 Feb 2026 19:41:12 +0100 [thread overview]
Message-ID: <87qzqsa1br.ffs@tglx> (raw)
In-Reply-To: <20260129215340.3742283-1-andrii@kernel.org>
On Thu, Jan 29 2026 at 13:53, Andrii Nakryiko wrote:
> /* unlock vma or mmap_lock, and put mm_struct before copying data to user */
> query_vma_teardown(&lock_ctx);
> mmput(mm);
>
> + if (karg.build_id_size) {
> + __u32 build_id_sz;
> +
> + if (vm_file)
> + err = build_id_parse_file(vm_file, build_id_buf, &build_id_sz);
> + else
> + err = -ENOENT;
> + if (err) {
> + karg.build_id_size = 0;
> + } else {
> + if (karg.build_id_size < build_id_sz) {
> + err = -ENAMETOOLONG;
> + goto out;
Introduces a double mmput() here.
> + }
> + karg.build_id_size = build_id_sz;
> + }
> + }
> +
> + if (vm_file)
> + fput(vm_file);
> +
> if (karg.vma_name_size && copy_to_user(u64_to_user_ptr(karg.vma_name_addr),
> name, karg.vma_name_size)) {
> kfree(name_buf);
> @@ -798,6 +808,8 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg)
> out:
> query_vma_teardown(&lock_ctx);
> mmput(mm);
> + if (vm_file)
> + fput(vm_file);
> kfree(name_buf);
> return err;
See:
https://lore.kernel.org/all/698aaf3c.050a0220.3b3015.0088.GAE@google.com/T/#u
Thanks
tglx
next prev parent reply other threads:[~2026-02-10 18:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-29 21:53 Andrii Nakryiko
2026-01-30 3:54 ` kernel test robot
2026-01-30 20:11 ` Andrii Nakryiko
2026-01-30 20:42 ` Andrew Morton
2026-01-30 20:47 ` Andrii Nakryiko
2026-01-30 4:40 ` Shakeel Butt
2026-01-30 6:43 ` kernel test robot
2026-02-10 18:41 ` Thomas Gleixner [this message]
2026-02-10 19:04 ` [BUG] " Andrii Nakryiko
2026-02-10 21:05 ` [PATCH] procfs: Prevent double mmput() in do_procmap_query() Thomas Gleixner
2026-02-11 11:58 ` Sebastian Andrzej Siewior
2026-02-11 17:24 ` Andrii Nakryiko
2026-02-11 17:29 ` Sebastian Andrzej Siewior
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