From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F144C37C0E6; Wed, 10 Jun 2026 19:53:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781121188; cv=none; b=i4OhQGlx1i02p1xNTfL35zsX0XRFRFOnSuoB/2G796pt7YCSsjXPFQL9NYcCYr0hvGgos/JD1h9nwT+6BR4Y+xkYp3nRWtecsVAEa+SYNagu29AuSdhBuORoCJtZ0kiPtLiZ2c61rDrlu61HR6YjZBs5ZXtAHRLwkOrU1Rf83DI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781121188; c=relaxed/simple; bh=+8XPQe1Y4G3gYkzSQUgluVBV493l2yWRMPBLtMvcfLA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=mS79qGSbZXnULf7uSpJ4H48EP8hcXP6C4yeeHtgrWdtaLqwQ1U8Dn6B1+DVRyRxwrIUHt4tNkcoNeFCYZTVeQuHwM1nv31y3aPzIKB2GeNQJ8EdNtVr7FpE83hMXdLlKB2yJfzbPaSizzc0qoHGcj5Mb0KGOkRgv39LWnL4IM7k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nE46ZsDs; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nE46ZsDs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00D231F00899; Wed, 10 Jun 2026 19:53:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781121187; bh=cSZ5kU4pTEcqxVD47lTugGIAYK1E5U/B002HFV83qew=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nE46ZsDs+5LrA4sqLGfURmXCLAVVz2B5Zwn7SzDYHLn4J1v7OAaE3j0+ZqF3TF8Px gw7zlJkfCZlOCdXRnQbbk5uRDvpbagrh70bbZhcqz5S8xPbYg4BD9uxvFgwy5umX60 zE3cdoPpEvMdhqH0jqV03ivNdwY3N5SrvcdnPNe8SYPwaCEBQtLhn7V8+i0eFQZyzq 4bJEEZAmYkYm1+gnR2eEw6YhXXTespb3bJsATuO1wJNzvALnWQ8n7cqDQVEgdvXH25 p/95rHxTiWv1nmac48iPXPKr2552O285B/UZfQmfC1tyqZukVwGVZ6GodHZS2KhUkj 2mz3Ol9fbxtbg== From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , sashiko-bot , "Claude Opus 4.6" Subject: [PATCH 12/23] perf symbols: Bounds-check descsz in sysfs__read_build_id() GNU fallback Date: Wed, 10 Jun 2026 16:51:45 -0300 Message-ID: <20260610195157.2091137-13-acme@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260610195157.2091137-1-acme@kernel.org> References: <20260610195157.2091137-1-acme@kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo When sysfs__read_build_id() matches NT_GNU_BUILD_ID with the right namesz but the name content is not "GNU", it falls back to reading descsz bytes into the stack buffer bf[BUFSIZ]: } else if (read(fd, bf, descsz) != (ssize_t)descsz) Unlike the else branch which validates namesz + descsz against sizeof(bf), this path passes descsz directly to read() without any bounds check. A crafted sysfs file with a large n_descsz overflows the 8192-byte stack buffer. Add a descsz > sizeof(bf) check before the read, breaking out of the loop on oversized values. Fixes: e5a1845fc0aeca85 ("perf symbols: Split out util/symbol-elf.c") Reported-by: sashiko-bot Cc: Namhyung Kim Assisted-by: Claude Opus 4.6 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol-elf.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 36a0304707e13138..06cfb84f86eb2f64 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -961,8 +961,13 @@ int sysfs__read_build_id(const char *filename, struct build_id *bid) err = 0; break; } - } else if (read(fd, bf, descsz) != (ssize_t)descsz) - break; + } else { + /* descsz from untrusted file — clamp to buffer */ + if (descsz > sizeof(bf)) + break; + if (read(fd, bf, descsz) != (ssize_t)descsz) + break; + } } else { size_t n; -- 2.54.0