From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D60CD154B4 for ; Wed, 9 Aug 2023 11:13:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5ADEDC433C8; Wed, 9 Aug 2023 11:13:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691579602; bh=6vGXeVQlHc4YB0qM9k27AkeH/leB3WiFtiewHLBer80=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yG8cQNSib85fdHomKo4iWC7HKmbkjDXhWsZB0yre4SIJ4T73owx2kwNpIcoPKaOmX kTvnbsCxhQGSUP3TyB8JKcSpCvYETNfidJUWcPuN3tp36/HzOIbHLJhMQzCX1rbGex 24JaH1XPNL+GtuaAu1DZoIHPnUJVpg7l/IXMFMgU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeremy Sowden , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 4.19 050/323] lib/ts_bm: reset initial match offset for every block of text Date: Wed, 9 Aug 2023 12:38:08 +0200 Message-ID: <20230809103700.417755763@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103658.104386911@linuxfoundation.org> References: <20230809103658.104386911@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeremy Sowden [ Upstream commit 6f67fbf8192da80c4db01a1800c7fceaca9cf1f9 ] The `shift` variable which indicates the offset in the string at which to start matching the pattern is initialized to `bm->patlen - 1`, but it is not reset when a new block is retrieved. This means the implemen- tation may start looking at later and later positions in each successive block and miss occurrences of the pattern at the beginning. E.g., consider a HTTP packet held in a non-linear skb, where the HTTP request line occurs in the second block: [... 52 bytes of packet headers ...] GET /bmtest HTTP/1.1\r\nHost: www.example.com\r\n\r\n and the pattern is "GET /bmtest". Once the first block comprising the packet headers has been examined, `shift` will be pointing to somewhere near the end of the block, and so when the second block is examined the request line at the beginning will be missed. Reinitialize the variable for each new block. Fixes: 8082e4ed0a61 ("[LIB]: Boyer-Moore extension for textsearch infrastructure strike #2") Link: https://bugzilla.netfilter.org/show_bug.cgi?id=1390 Signed-off-by: Jeremy Sowden Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- lib/ts_bm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/ts_bm.c b/lib/ts_bm.c index 9e66ee4020e90..5de382e79a45a 100644 --- a/lib/ts_bm.c +++ b/lib/ts_bm.c @@ -64,10 +64,12 @@ static unsigned int bm_find(struct ts_config *conf, struct ts_state *state) struct ts_bm *bm = ts_config_priv(conf); unsigned int i, text_len, consumed = state->offset; const u8 *text; - int shift = bm->patlen - 1, bs; + int bs; const u8 icase = conf->flags & TS_IGNORECASE; for (;;) { + int shift = bm->patlen - 1; + text_len = conf->get_next_block(consumed, &text, conf, state); if (unlikely(text_len == 0)) -- 2.39.2