From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f172.google.com (mail-dy1-f172.google.com [74.125.82.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F335332E6BB for ; Tue, 5 May 2026 23:02:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778022153; cv=none; b=ODwLAF6wSdsT9+nEXJsoNRyCBl8U6A7Qi7b3Ycu2t668vxMiKI4+aRIRKCR3JbjZ9olQkYJi9CfCjoc8hEjzCEZRkBnhvv5RH2xR6elMDkh7kgZD7SZEPcc3zmT25pMxGrOyI/pSgI6ATxanY6SfTRHEkHaS6bLCGKulHIeQNYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778022153; c=relaxed/simple; bh=fX4OvBVV8Pd7ppnT5E3rnJzlKJlg/3XrfBXMkyWB0oY=; h=Message-Id:In-Reply-To:References:From:Date:Subject:Content-Type: MIME-Version:To:Cc; b=SAlJuOADPkJzuwqborUCr6CoQZJ0P/GElflkQcQ4ctuGz0VqTdJeqhwJt40oZlDZxbMq7WKLe8FFfASeQcyWp8bnPTUFb0O0Zp02eRczV3aN2K5RMpgDDoHCous0cTonRUKHYTiKiFDsPfaoKyZHu8jUx4mxWQwr7Gq9HqLCPNg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kYHLj+yb; arc=none smtp.client-ip=74.125.82.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kYHLj+yb" Received: by mail-dy1-f172.google.com with SMTP id 5a478bee46e88-2f00a567cfaso300763eec.0 for ; Tue, 05 May 2026 16:02:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778022151; x=1778626951; darn=vger.kernel.org; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:from:to:cc:subject:date :message-id:reply-to; bh=vcLsdeWMhUMQPfZNq5JY+8B03eHo1E5r5hp/TD9BEIk=; b=kYHLj+ybdKLyCsGDeyrpQWBnL9pbrvRTdC6Xfxjkc/h5bRg6v7e5O8jH8xREiJB7i5 m1IJuL/x7qXj0E/PemlYbAElK5e/CSipWfLfCgt+z6/YZLTmhad422HePhagJfKCcOEq ARzFG50VO7A15UlsvXJIzM3/Edc746sfdcfaJdlMVFKO7NRyqc0i3w+4lDHvDoqrCUvJ J4mf6+x5JPignDQpGV9nKAQuUH0B/qGffpd7Ivj45KkH+PXicd4AnSSqqzbCU+3cWQQt Dcbk86WGE/e7pE24rVpBCkuWZzu9a8j2WzYxtvMcEkquwk7Wq0tUQWiCpfm+rp/fz5eE VFCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778022151; x=1778626951; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=vcLsdeWMhUMQPfZNq5JY+8B03eHo1E5r5hp/TD9BEIk=; b=MvypdJjHs3oj16BQAe8/i5W1FsK+KsWVg6+3XG+UCphf5ZfIUNrXEAETuFvGDYEMxf cwoWCrZSozgVHH8GbY/OJZFjCdUltGR5S+xD/msyR+cV7aIs9Pn934ZYlDZuIpe/sOvG dGDOIJfwbi6M+tZ73sRlEGCasjoQjBCppi5lBiqc4TYwu/PV/kwWzZlTNLtoZyQ/MrxU K35BQEhU4cXcuyns8rD/D0XnaytktB9bRxstz2OjSYjPnju+SsHuKBrqST5XHKesk20K djSGZ1M3Byd1b+aOBGKvD2Z53PVEnEL1RpIurDg53agxK4ZG92MS5p4X4Myn8i1LF8Mf vPnQ== X-Gm-Message-State: AOJu0YzpppD/UFHVQBiyVyKruBS1aKZu3XP5feB+7zEA9Rd1Nz3h3eCu jhtwPFplco4f4LlQuTUkC88S4265VkWWET8FxmV/yQ1VEfb4kajn+H8hnkkGgwNY X-Gm-Gg: AeBDievobTiifo1dkV9paEdEmj2k+RYfPpkiLxWNcPMjt21IHpQWQ/v75sINxYdrqzS ROHNWpG1144Wc45c1FRYBU0XiV1iPz67jtFdbWAr35bnCoVw5GH/qHwMsUpjxhrTcE2PjkGDkBc F1lJx2oSyDYvZT0cOV0+iU6Lc58GaovjNjsKoEGLZ4jqVzeExOAXffBzfa+drXNnDU/Y/i9onUV dv+3uLbpOpdxBVMwohumw2Ikd4aRrDkavZy17kOZCAhItHefOHl+5WTkONsW9tLNDMRq/wxVSX6 0QjncMcy3Reppx6kHWggSlrJbrXQLFIz3oSbd9coLNTn8Onop7q34Xh9yvKlHBodt18hCwlzAkL BqTzpL7Ltl7ZgycEXlrpKr5KRw53UcWLiKxdPV/9nMffxJHjokorsIg+d2kCNfsqEdz1S3pXaJ0 hAsmZ3a1JpOUB8BTRR1dnO4Mmz1jjwni15 X-Received: by 2002:a05:7300:b10b:b0:2f3:b7b2:cbd3 with SMTP id 5a478bee46e88-2f558c796cdmr385805eec.5.1778022150246; Tue, 05 May 2026 16:02:30 -0700 (PDT) Received: from [127.0.0.1] ([20.168.4.2]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2f56cec58efsm902968eec.2.2026.05.05.16.02.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2026 16:02:29 -0700 (PDT) Message-Id: In-Reply-To: References: From: "Michael Montalbo via GitGitGadget" Date: Tue, 05 May 2026 23:02:23 +0000 Subject: [PATCH 3/4] xdiff: guard against negative context lengths Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 To: git@vger.kernel.org Cc: Michael Montalbo , Michael Montalbo From: Michael Montalbo The xdemitconf_t fields ctxlen and interhunkctxlen are typed as long (signed), but negative values are not meaningful for context line counts. Unlike the diff_options fields changed in the previous two commits, these cannot be converted to unsigned because the xdiff arithmetic relies on signed subtraction: s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0); If ctxlen were unsigned long, the signed operand would be implicitly converted to unsigned, and the subtraction would wrap to a large positive value when i1 < ctxlen, defeating the XDL_MAX clamp. The signed type is required for correct context-window calculations. The previous two commits reject negative values at the parse layer for --inter-hunk-context and -U/--unified, so negative values should no longer reach xdiff in normal use. Add BUG() guards at the top of xdl_get_hunk() as defense in depth to catch programming errors in current or future callers that bypass option parsing. xdl_get_hunk() is called by both xdl_emit_diff() and xdl_call_hunk_func(), so a single guard covers all xdiff consumers. Signed-off-by: Michael Montalbo --- xdiff/xemit.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/xdiff/xemit.c b/xdiff/xemit.c index 04f7e9193b..7cd9cf0a44 100644 --- a/xdiff/xemit.c +++ b/xdiff/xemit.c @@ -46,12 +46,20 @@ static long saturating_add(long a, long b) xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg) { xdchange_t *xch, *xchp, *lxch; - long max_common = saturating_add(saturating_add(xecfg->ctxlen, - xecfg->ctxlen), - xecfg->interhunkctxlen); - long max_ignorable = xecfg->ctxlen; + long max_common; + long max_ignorable; long ignored = 0; /* number of ignored blank lines */ + if (xecfg->ctxlen < 0) + BUG("negative context length: %ld", xecfg->ctxlen); + if (xecfg->interhunkctxlen < 0) + BUG("negative inter-hunk context length: %ld", xecfg->interhunkctxlen); + + max_common = saturating_add(saturating_add(xecfg->ctxlen, + xecfg->ctxlen), + xecfg->interhunkctxlen); + max_ignorable = xecfg->ctxlen; + /* remove ignorable changes that are too far before other changes */ for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) { xch = xchp->next; -- gitgitgadget