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 40D681862; Wed, 29 Jul 2026 00:28:11 +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=1785284893; cv=none; b=KeObJFzaFq6FMNBssG6LfX64OwwAKcKt8yqOjluFylxWH+cujIqgjxITjVwopw2IahbGZ+48WHigmJ1ZCBezwdg4a/uGG2/MsGPxbZiOOKnF/I3lPBswQ+eze+KryUbEiAoy4DKhP3XAGR6wNzuUOCrDA6Jkb0D+EHDJUHha2m0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785284893; c=relaxed/simple; bh=a+hZxuvFRPZ7ZbEkU+xDHLS8Z3q5N5kXPm/pbfPFVZg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XJN4E9gj4O5fgm8pfq+y059BiM5OKjtnhyXQfEsso5Xz2pQTgRhH0ruSORvR8ZRODpAZOuRBD2DF7FcwDkZ7bHWEOss4Ngk8KhN/hq/9iahV0+tRNWAAFYAlb9wWF5Et53kzvMk2Lmwdm5FUcDEYk+GxC2HRckYkwY8mIhnIP/0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aOpQRu53; 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="aOpQRu53" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CC211F000E9; Wed, 29 Jul 2026 00:28:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785284891; bh=m8TvUx6M6Hg7FbTl7Wkwe3DNlTRDm6WOwra9w0aa+HQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aOpQRu53FHR+eDxKxiQdPKKxIM+Q5YImN4GnK2cxHTNaNLdq2x+DE0pDosvPWnmSN zYCw9zzexaqSsG63qLNJ4BtSd2pEYXa5ZQfAYv8tuWlxV71PnRqetgy0ZNxUBSUH1x G0Vbo9qSzLP4t8ss73i8pKbcFE4vTXLmX9m49I3npGnknIaZQSaTXHfvwuZlKq6bww V6g/GmWeise4s0ynyxqeAByOfgI8DCD6CyDdbW7jRXuTNajaLJhe5ZentmSWyr2Vk6 0hOK28IieLP/tpcQHD8PTs3/BiVwhmkQZ92q8QZGNtJcLf6fCInv+Lheixt8T37/Qk ae2jYW2GKgaDQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH 2/2] tracing/filters: Fix false positive match in regex_match_full() Date: Wed, 29 Jul 2026 09:28:07 +0900 Message-ID: <178528488779.124250.5571741156199253769.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178528486942.124250.10437463913796837242.stgit@devnote2> References: <178528486942.124250.10437463913796837242.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@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: Masami Hiramatsu (Google) regex_match_full() calls strncmp(str, r->pattern, len) where len is the target field buffer size. When len is smaller than r->len (the filter pattern length), strncmp() checks only len bytes of r->pattern against str. If those len bytes match, strncmp() returns 0, resulting in a false-positive match where a shorter string in a fixed-size field matches a longer filter pattern. For example, a 4-byte static string field containing "abcd" matched the filter pattern "abcdefgh" because strncmp("abcd", "abcdefgh", 4) returned 0. In this case, @len does NOT include '\0' because it is fixed-size array. Fix this by returning 0 (no match) early when len < r->len. Fixes: 1889d20922d1 ("tracing/filters: Provide basic regex support") Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_events_filter.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 6385cd662d8d..2b46ca536045 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1027,6 +1027,9 @@ static int regex_match_full(char *str, struct regex *r, int len) if (!len) return strcmp(str, r->pattern) == 0; + if (len < r->len) + return 0; + return strncmp(str, r->pattern, len) == 0; }