Subject: [PATCH] treewide: fix various bugs w/ OpenSSL 3+ EVP API

From: Eric Wong <[email-masked]>
Date: Fri, 1 Sep 2023 02:09:28 +0000

The OpenSSL 3+ EVP API for SHA-* cannot support our prior use cases
supported by other SHA-* implementations.  It has the following
differences:

1. ->init_fn is required before all use
2. struct assignments don't work and requires ->clone_fn
3. can't support ->update_fn after ->final_*fn

While fixing cases 1 and 2 is merely the matter of calling ->init_fn and
->clone_fn as appropriate, fixing case 3 requires calling ->final_*fn on
a temporary context that's cloned from the primary context.

Reported-by: Bagas Sanjaya <[email-masked]>
Link: https://lore.kernel.org/[email-masked]/
Helped-by: brian m. carlson <[email-masked]>
Fixes: 3e440ea0aba0 ("sha256: avoid functions deprecated in OpenSSL 3+")
Fixes: bda9c12073e7 ("avoid SHA-1 functions deprecated in OpenSSL 3+")
Signed-off-by: Eric Wong <[email-masked]>
---
 Ugh, I wonder if I setup my config.mak incorrectly when testing
 3e440ea0aba0 and bda9c12073e7 :x

 There may be other misuses not exposed by the test suite.  Making
 git_hash_ctx opaque could flush out some of them (but I dislike
 APIs which force heap allocations in the first place).  In any case,
 I really wish git relied less on globals so object lifetimes could be
 more obvious and really wish all C projects could rely on
 gcc/tinycc/clang-supported __attribute__((__cleanup__)) to make
 lifetimes easier-to-manage...

 builtin/fast-import.c    | 1 +
 builtin/index-pack.c     | 5 ++++-
 builtin/unpack-objects.c | 5 ++++-
 bulk-checkin.c           | 1 +
 csum-file.c              | 2 +-
 5 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index 4dbb10aff3..444f41cf8c 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -1102,6 +1102,7 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 		|| (pack_size + PACK_SIZE_THRESHOLD + len) < pack_size)
 		cycle_packfile();
 
+	the_hash_algo->init_fn(&checkpoint.ctx);
 	hashfile_checkpoint(pack_file, &checkpoint);
 	offset = checkpoint.offset;
 
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 006ffdc9c5..dda94a9f46 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1166,6 +1166,7 @@ static void parse_pack_objects(unsigned char *hash)
 	struct ofs_delta_entry *ofs_delta = ofs_deltas;
 	struct object_id ref_delta_oid;
 	struct stat st;
+	git_hash_ctx tmp_ctx;
 
 	if (verbose)
 		progress = start_progress(
@@ -1202,7 +1203,9 @@ static void parse_pack_objects(unsigned char *hash)
 
 	/* Check pack integrity */
 	flush();
-	the_hash_algo->final_fn(hash, &input_ctx);
+	the_hash_algo->init_fn(&tmp_ctx);
+	the_hash_algo->clone_fn(&tmp_ctx, &input_ctx);
+	the_hash_algo->final_fn(hash, &tmp_ctx);
 	if (!hasheq(fill(the_hash_algo->rawsz), hash))
 		die(_("pack is corrupted (SHA1 mismatch)"));
 	use(the_hash_algo->rawsz);
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 32505255a0..fef7423448 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -609,6 +609,7 @@ int cmd_unpack_objects(int argc, const char **argv, const char *prefix UNUSED)
 {
 	int i;
 	struct object_id oid;
+	git_hash_ctx tmp_ctx;
 
 	disable_replace_refs();
 
@@ -669,7 +670,9 @@ int cmd_unpack_objects(int argc, const char **argv, const char *prefix UNUSED)
 	the_hash_algo->init_fn(&ctx);
 	unpack_all();
 	the_hash_algo->update_fn(&ctx, buffer, offset);
-	the_hash_algo->final_oid_fn(&oid, &ctx);
+	the_hash_algo->init_fn(&tmp_ctx);
+	the_hash_algo->clone_fn(&tmp_ctx, &ctx);
+	the_hash_algo->final_oid_fn(&oid, &tmp_ctx);
 	if (strict) {
 		write_rest();
 		if (fsck_finish(&fsck_options))
diff --git a/bulk-checkin.c b/bulk-checkin.c
index 73bff3a23d..92b9c8598b 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -268,6 +268,7 @@ static int deflate_to_pack(struct bulk_checkin_packfile *state,
 					  type, size);
 	the_hash_algo->init_fn(&ctx);
 	the_hash_algo->update_fn(&ctx, obuf, header_len);
+	the_hash_algo->init_fn(&checkpoint.ctx);
 
 	/* Note: idx is non-NULL when we are writing */
 	if ((flags & HASH_WRITE_OBJECT) != 0)
diff --git a/csum-file.c b/csum-file.c
index cd01713244..870748e016 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -207,7 +207,7 @@ int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint
 	    lseek(f->fd, offset, SEEK_SET) != offset)
 		return -1;
 	f->total = offset;
-	f->ctx = checkpoint->ctx;
+	the_hash_algo->clone_fn(&f->ctx, &checkpoint->ctx);
 	f->offset = 0; /* hashflush() was called in checkpoint */
 	return 0;
 }