Re: [PATCH v7 23/28] Reftable support for git-core
flat view
From: Andrzej Hunt <hidden>
Date: 2021-05-04 17:24:30
On 19/04/2021 13:37, Han-Wen Nienhuys via GitGitGadget wrote:
From: Han-Wen Nienhuys <redacted>
[...snip...]> diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
quoted hunk ↗ jump to hunk
new file mode 100644 index 000000000000..55d053e5ca65--- /dev/null +++ b/refs/reftable-backend.c
[...snip...]
quoted hunk ↗ jump to hunk
+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
quoted hunk ↗ jump to hunk
+ + /* 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; +} +
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