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Bug#866011: git: FTBFS on sparc64 due to unaligned access in pack-bitmap.c

Source: git
Version: 1:2.13.0+next.20170520-1
Severity: important
Tags: patch upstream
User: debian-sparc@lists.debian.org
Usertags: sparc64
X-Debbugs-Cc: debian-sparc@lists.debian.org

New tests added upstream have been causing git to FTBFS on sparc64 due
to a not-previously-noticed unaligned access in pack-bitmap. Please find
attached the patch submitted upstream (mailing list index has not yet
updated, hence the lack of a Forwarded:).

From: James Clarke <jrtc27@jrtc27.com>
To: gitster@pobox.com
Cc: James Clarke <jrtc27@jrtc27.com>,
Subject: [PATCH] pack-bitmap: Don't perform unaligned memory access
Date: Mon, 26 Jun 2017 16:16:12 +0100
Message-Id: <20170626151612.64019-1-jrtc27@jrtc27.com>
X-Mailer: git-send-email 2.13.2

The preceding bitmap entries have a 1-byte XOR-offset and 1-byte flags,
so their size is not a multiple of 4. Thus the name-hash cache is only
guaranteed to be 2-byte aligned and so we must use get_be32 rather than
indexing the array directly.

Signed-off-by: James Clarke <jrtc27@jrtc27.com>

This was noticed thanks to the recent tests added to t5310-pack-bitmaps.sh,
which were crashing with SIGBUS on Debian sparc64. All tests (excluding those
marked with known breakage) now pass again.

 pack-bitmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pack-bitmap.c b/pack-bitmap.c
index a3ac3dccd..327634cd7 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -627,7 +627,7 @@ static void show_objects_for_type(
 			sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);

 			if (bitmap_git.hashes)
-				hash = ntohl(bitmap_git.hashes[entry->nr]);
+				hash = get_be32(bitmap_git.hashes + entry->nr);

 			show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);

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