From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cloud.peff.net (cloud.peff.net [217.216.95.84]) (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 5BBF94AD4C7 for ; Wed, 30 Sep 2026 23:44:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.216.95.84 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790811845; cv=none; b=GYzFzlp8iS4WVAKld0LyHrIWUeRFEudAqNjB7MF9kXQtRLTxBrqp1wnSyGKG7oNK5YXI/PbZ3pLaG0nOeZVqC18RgkN8bVYYSw2dB4IaDsNhrxZNiDeX6uCMg7Oyy8s8BNqnnS0aY5nX2kmstfUn1pc7O+hPD6iNQP6UgK/Kluo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790811845; c=relaxed/simple; bh=yu57GJ5Pi+P9z0S+aTQNOao64HX/tB5izHI6Y1qxGAU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=szJiTGYZNMddex1lkpOJl85/8b+sb4eoGpo7R5Vh41u0Al20my9b9pykYB0TRF0OKOk344Y0zY2jyLNWsC+azrYOLes4Pcn353Xm5g0XWh75jsEV0vGLO1RImTgWVJH5XCkch/iQHcIj/RMpqxIvavmppqIIJlsMnE9E1nqyZuo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=peff.net; spf=pass smtp.mailfrom=peff.net; dkim=pass (2048-bit key) header.d=peff.net header.i=@peff.net header.b=R6mBpduU; arc=none smtp.client-ip=217.216.95.84 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=peff.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=peff.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=peff.net header.i=@peff.net header.b="R6mBpduU" Received: (qmail 8153 invoked by uid 106); 30 Sep 2026 23:44:03 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=peff.net; h=date:from:to:cc:subject:message-id:references:mime-version:content-type:in-reply-to; s=20240930; bh=yu57GJ5Pi+P9z0S+aTQNOao64HX/tB5izHI6Y1qxGAU=; b=R6mBpduU/8IigxOIxmR+1DPknyzkYKL9n9GztJlWtJ5phFhuW34it0E55Tf85NIDjzbLpmuY1weY6OJduGQ7Zd3H6UIsJEiuZMYB4CeVgNDCsY4IxsV2Tp4VhfF/dmzlRQqmmPsnfl88tEemkAsYqE8jCSRMQKFHHavf3u6lEFDWk0hv57DLsCwUlTzS7VKun6CYOl28YgfYiLNCAd5XHrZX+obBPmyRI4HegPpfkYgkhM5sIQ4urhaKWJmn32EoTKxdquuFk/gMv/DeQSbXeeg0oaYqUIe/Di6oDS6bls09vlq7XkcwDmk6h10BoOu5dJuPdPPyO55zMhVykP4CNA== Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Wed, 30 Sep 2026 23:44:03 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 20816 invoked by uid 111); 30 Sep 2026 23:44:05 -0000 Received: from coredump.intra.peff.net (HELO coredump.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Wed, 30 Sep 2026 19:44:05 -0400 Authentication-Results: peff.net; auth=none Date: Wed, 30 Sep 2026 19:44:02 -0400 From: Jeff King To: git@vger.kernel.org Cc: Junio C Hamano , Patrick Steinhardt , Elijah Newren Subject: [PATCH v2 1/7] xdiff: clean up read_mmfile() allocations on error Message-ID: <20260930234402.GA1347555@coredump.intra.peff.net> References: <20260930234348.GA1340390@coredump.intra.peff.net> Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260930234348.GA1340390@coredump.intra.peff.net> When read_mmfile() returns an error, it may or may not have allocated a buffer in the passed-in mmfile_t. So callers must initialize the pointer to NULL and free it even on error. Most callers do this already, but rerere's diff_two() does not, and would leak the buffer after a read error. We could fix it directly, but let's instead try to make the interface less error-prone by freeing the memory when returning failure from read_mmfile(). This fixes (part of) the leak in diff_two(). In theory it also lets us simplify other callers to skip initializing the mmfile. But in practice most still need zero-initialization because they may jump to free() before even calling read_mmfile (e.g., in try_merge()). But we can at least simplify rerere_forget_one_path() a bit. I said "part of" earlier. There's a related leak in diff_two(): if reading the first file succeeds but reading the second fails, we return early and leak the first buffer. We can fix that by checking each individually. Signed-off-by: Jeff King --- builtin/rerere.c | 6 +++++- rerere.c | 3 +-- xdiff-interface.c | 1 + 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/builtin/rerere.c b/builtin/rerere.c index a056cb791b..d39c6e8445 100644 --- a/builtin/rerere.c +++ b/builtin/rerere.c @@ -34,8 +34,12 @@ static int diff_two(const char *file1, const char *label1, mmfile_t minus, plus; int ret; - if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2)) + if (read_mmfile(&minus, file1)) return -1; + if (read_mmfile(&plus, file2)) { + free(minus.ptr); + return -1; + } printf("--- a/%s\n+++ b/%s\n", label1, label2); fflush(stdout); diff --git a/rerere.c b/rerere.c index 1c3745d9e3..856347c9ae 100644 --- a/rerere.c +++ b/rerere.c @@ -1039,7 +1039,7 @@ static int rerere_forget_one_path(struct index_state *istate, for (id->variant = 0; id->variant < id->collection->status_nr; id->variant++) { - mmfile_t cur = { NULL, 0 }; + mmfile_t cur; mmbuffer_t result = {NULL, 0}; int cleanly_resolved; @@ -1048,7 +1048,6 @@ static int rerere_forget_one_path(struct index_state *istate, handle_cache(istate, path, hash, rerere_path(&buf, id, "thisimage")); if (read_mmfile(&cur, rerere_path(&buf, id, "thisimage"))) { - free(cur.ptr); error(_("failed to update conflicted state in '%s'"), path); goto fail_exit; } diff --git a/xdiff-interface.c b/xdiff-interface.c index db6938689f..e3dd2184ae 100644 --- a/xdiff-interface.c +++ b/xdiff-interface.c @@ -168,6 +168,7 @@ int read_mmfile(mmfile_t *ptr, const char *filename) sz = xsize_t(st.st_size); ptr->ptr = xmalloc(sz ? sz : 1); if (sz && fread(ptr->ptr, sz, 1, f) != 1) { + FREE_AND_NULL(ptr->ptr); fclose(f); return error("Could not read %s", filename); } -- 2.56.0.354.gb6b32d5be5