From: Andrzej Hunt Date: Tue, 04 May 2021 17:24:20 GMT Subject: Re: [PATCH v7 23/28] Reftable support for git-core Message-ID: In-Reply-To: <2fd7cb8c0983501e2af2f195aec81d7c17fb80e1.1618832277.git.gitgitgadget@gmail.com> On 19/04/2021 13:37, Han-Wen Nienhuys via GitGitGadget wrote: > From: Han-Wen Nienhuys [...snip...]> diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c > new file mode 100644 > index 000000000000..55d053e5ca65 > --- /dev/null > +++ b/refs/reftable-backend.c [...snip...] > +static int write_transaction_table(struct reftable_writer *writer, void *arg) > +{ > + struct ref_transaction *transaction = (struct ref_transaction *)arg; > + struct git_reftable_ref_store *refs = > + (struct git_reftable_ref_store *)transaction->ref_store; > + struct reftable_stack *stack = > + stack_for(refs, transaction->updates[0]->refname); > + uint64_t ts = reftable_stack_next_update_index(stack); > + int err = 0; > + int i = 0; > + struct reftable_log_record *logs = > + calloc(transaction->nr, sizeof(*logs)); > + struct ref_update **sorted = > + malloc(transaction->nr * sizeof(struct ref_update *)); > + struct reftable_merged_table *mt = reftable_stack_merged_table(stack); > + struct reftable_table tab = {NULL}; > + struct reftable_ref_record ref = {NULL}; > + reftable_table_from_merged_table(&tab, mt); > + COPY_ARRAY(sorted, transaction->updates, transaction->nr); > + QSORT(sorted, transaction->nr, ref_update_cmp); > + reftable_writer_set_limits(writer, ts, ts); > + > + for (i = 0; i < transaction->nr; i++) { > + struct ref_update *u = sorted[i]; > + struct reftable_log_record *log = &logs[i]; > + struct object_id old_id; > + fill_reftable_log_record(log); > + log->update_index = ts; > + log->value_type = REFTABLE_LOG_UPDATE; > + log->refname = (char *)u->refname; > + log->update.new_hash = u->new_oid.hash; > + log->update.message = u->msg; > + > + err = reftable_table_read_ref(&tab, u->refname, &ref); > + if (err < 0) > + goto done; > + else if (err > 0) { > + old_id = null_oid; > + } else { > + oidread(&old_id, ref.value.val1); > + } This seems to assume that 'ref.value_type == REFTABLE_REF_VAL1' - but do we expect to have to handle the other types (REFTABLE_REF_VAL2/REFTABLE_REF_SYMREF)? When I run tests in seen against ASAN I see the following errors in t0031, which suggests we're running this code against REFTABLE_REF_SYMREF too - but I don't know if that means that this code should be able to handle the other ref types or if there's a bug higher up the stack. (AFAIUI REFTABLE_REF_DELETION is already handled because reftable_table_read_ref() already returns 1 for deletion, but the other cases seem valid?) ASAN error output: ==25352==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000003353 at pc 0x000000499d17 bp 0x7fff0ea0a210 sp 0x7fff0ea099d8 READ of size 32 at 0x603000003353 thread T0 #0 0x499d16 in __asan_memcpy ../projects/compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp:22:3 #1 0x97ed0a in oidread hash.h:292:2 #2 0x97ed0a in write_transaction_table refs/reftable-backend.c:548:4 #3 0xb5537a in reftable_addition_add reftable/stack.c:650:8 #4 0x97b024 in git_reftable_transaction_finish refs/reftable-backend.c:618:9 #5 0x95f9bf in ref_transaction_commit refs.c:2218:8 #6 0x9d3aa6 in update_head_with_reflog sequencer.c:1138:6 #7 0x52ffbf in cmd_commit builtin/commit.c:1814:6 #8 0x4ce8fe in run_builtin git.c:461:11 #9 0x4ccbc8 in handle_builtin git.c:718:3 #10 0x4cb0cc in run_argv git.c:785:4 #11 0x4cb0cc in cmd_main git.c:916:19 #12 0x6beded in main common-main.c:52:11 #13 0x7f415c762349 in __libc_start_main (/lib64/libc.so.6+0x24349) #14 0x420769 in _start ../sysdeps/x86_64/start.S:120 0x603000003353 is located 0 bytes to the right of 19-byte region [0x603000003340,0x603000003353) allocated by thread T0 here: #0 0x4868b4 in strdup ../projects/compiler-rt/lib/asan/asan_interceptors.cpp:452:3 #1 0xaa08e8 in xstrdup wrapper.c:29:14 #2 0xb4b280 in reftable_ref_record_copy_from reftable/record.c:229:23 #3 0xb46754 in merged_iter_next_entry reftable/merged.c:132:2 #4 0xb46754 in merged_iter_next reftable/merged.c:141:13 #5 0xb46754 in merged_iter_next_void reftable/merged.c:157:9 #6 0xb500ae in iterator_next reftable/generic.c:147:9 #7 0xb500ae in reftable_iterator_next_ref reftable/generic.c:134:9 #8 0xb500ae in reftable_table_read_ref reftable/generic.c:46:8 #9 0x97ec67 in write_transaction_table refs/reftable-backend.c:542:9 #10 0xb5537a in reftable_addition_add reftable/stack.c:650:8 #11 0x97b024 in git_reftable_transaction_finish refs/reftable-backend.c:618:9 #12 0x95f9bf in ref_transaction_commit refs.c:2218:8 #13 0x9d3aa6 in update_head_with_reflog sequencer.c:1138:6 #14 0x52ffbf in cmd_commit builtin/commit.c:1814:6 #15 0x4ce8fe in run_builtin git.c:461:11 #16 0x4ccbc8 in handle_builtin git.c:718:3 #17 0x4cb0cc in run_argv git.c:785:4 #18 0x4cb0cc in cmd_main git.c:916:19 #19 0x6beded in main common-main.c:52:11 #20 0x7f415c762349 in __libc_start_main (/lib64/libc.so.6+0x24349) SUMMARY: AddressSanitizer: heap-buffer-overflow ../projects/compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp:22:3 in __asan_memcpy Produced using: make CC=clang-11 SANITIZE=address COPTS="-Og -g" GIT_TEST_OPTS=-v T=t0031-reftable.sh test > + > + /* XXX fold together with the old_id check below? */ > + > + log->update.old_hash = old_id.hash; > + if (u->flags & REF_LOG_ONLY) { > + continue; > + } > + > + if (u->flags & REF_HAVE_NEW) { > + struct reftable_ref_record ref = { NULL }; > + struct object_id peeled; > + > + int peel_error = peel_object(&u->new_oid, &peeled); > + ref.refname = (char *)u->refname; > + ref.update_index = ts; > + > + if (!peel_error) { > + ref.value_type = REFTABLE_REF_VAL2; > + ref.value.val2.target_value = peeled.hash; > + ref.value.val2.value = u->new_oid.hash; > + } else if (!is_null_oid(&u->new_oid)) { > + ref.value_type = REFTABLE_REF_VAL1; > + ref.value.val1 = u->new_oid.hash; > + } > + > + err = reftable_writer_add_ref(writer, &ref); > + if (err < 0) { > + goto done; > + } > + } > + } > + > + for (i = 0; i < transaction->nr; i++) { > + err = reftable_writer_add_log(writer, &logs[i]); > + clear_reftable_log_record(&logs[i]); > + if (err < 0) { > + goto done; > + } > + } > + > +done: > + assert(err != REFTABLE_API_ERROR); > + reftable_ref_record_release(&ref); > + free(logs); > + free(sorted); > + return err; > +} > + [...snip...]