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Tue, 10 Feb 2026 11:04:55 -0800 (PST) MIME-Version: 1.0 References: <20260129215340.3742283-1-andrii@kernel.org> <87qzqsa1br.ffs@tglx> In-Reply-To: <87qzqsa1br.ffs@tglx> From: Andrii Nakryiko Date: Tue, 10 Feb 2026 11:04:42 -0800 X-Gm-Features: AZwV_QioTD-2tB90VI5wBvuDYhjyIi8I9OHw4H2v3xPsXfvoZ1RNWowMJzaHBTc Message-ID: Subject: Re: [BUG] [PATCH v2 mm-stable] procfs: avoid fetching build ID while holding VMA lock To: Thomas Gleixner Cc: Andrii Nakryiko , akpm@linux-foundation.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, surenb@google.com, shakeel.butt@linux.dev, syzbot+4e70c8e0a2017b432f7a@syzkaller.appspotmail.com, syzbot+237b5b985b78c1da9600@syzkaller.appspotmail.com, Peter Zijlstra , Sebastian Andrzej Siewior Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: odjxcnps7qxga7oqqxtijjkekod5484f X-Rspamd-Queue-Id: 94EC41C0003 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1770750296-228282 X-HE-Meta: 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 ClUiAMTc tuolk8GZVYuJWhTMryjvFF2QPxCVg86sMjgsGHsprYapJkFRCIRqTPLTgWI0jF2HQsqkfhIE6+8gz9HmePM9xF5vVM1vNc6Q/Cp0l1uEOe2dnaAv+5SUMozY6hDKeMPrEt9hsdnw+q8f6XgSIWeswPvnzXR7hGjeYHdHvPkNH+Hyk3UPtqhpzAkgwK4TzHAk90OGsWsz3Gz5Q7EIF/T8+0wBlSw== 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: List-Subscribe: List-Unsubscribe: On Tue, Feb 10, 2026 at 10:41=E2=80=AFAM Thomas Gleixner = wrote: > > 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 =3D build_id_parse_file(vm_file, build_id_buf= , &build_id_sz); > > + else > > + err =3D -ENOENT; > > + if (err) { > > + karg.build_id_size =3D 0; > > + } else { > > + if (karg.build_id_size < build_id_sz) { > > + err =3D -ENAMETOOLONG; > > + goto out; > > Introduces a double mmput() here. > > > + } > > + karg.build_id_size =3D build_id_sz; > > + } > > + } > > + > > + if (vm_file) > > + fput(vm_file); > > + > > if (karg.vma_name_size && copy_to_user(u64_to_user_ptr(karg.vma_n= ame_addr), > > name, karg.vma_name_size))= { > > kfree(name_buf); > > @@ -798,6 +808,8 @@ static int do_procmap_query(struct mm_struct *mm, v= oid __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@goo= gle.com/T/#u > Ah, silly mistake on my part, thanks for the heads up, I'll send a fix shor= tly > Thanks > > tglx