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fix: read scanner io_error before destroy (-m UAF); refuse an empty keep-set from an errored scan

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scan_directory_multithreaded read directory_scanner_had_io_error() /
parallel_scanner_had_io_error() AFTER destroying the scanner object (a
heap-use-after-free on every successful -m run that recorded an io_error); the
flag is now captured before the destroy.  As a second line of defense against
an empty-keep-set wipe, all four manifest send sites (sequential and -m, early
pre-scan and commit data pass) now refuse to transmit a keep-set manifest when
the scan that built it recorded an io_error and produced no keep entries: a
source that merely LOOKS empty because part of it was unreadable must never
delete the whole destination.  A genuinely empty source (no io_error) still
sends its empty keep-set and prunes extras.
This commit is contained in:
TapTap
2026-09-06 23:10:32 +02:00
parent b031e73ab0
commit 8007aed5f6
1 changed files with 55 additions and 5 deletions
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src/client/client_send.c
+55 -5
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@@ -628,7 +628,12 @@ static int send_list_only(const Config* config) {
/* Send the delete manifest (keep-set paths plus the protected excluded
prefixes) to the server. Returns 0 on success, -1 on failure. When
--delete-excluded is given `protected` is empty: excluded destination
mirrors are then ordinary extras and are removed. */
mirrors are then ordinary extras and are removed. Both sections are
unbounded on the sender; the receiver enforces MAX_MANIFEST_ENTRIES per
section and a single MAX_MANIFEST_BYTES budget shared across the two
sections, rejecting (with STATUS_ERROR) an over-budget frame. A heavily
filtered source whose exclusion list is large therefore fails the run
cleanly on the receiver rather than being truncated. */
static int send_delete_manifest(int fd, ArrayList* manifest, ArrayList* protected_prefixes) {
if (!manifest)
return -1;
@@ -1048,6 +1053,18 @@ static int send_chunks_multithreaded(void* pipeline_context) {
return thrd_error;
}
if (context->config->use_delete && !context->early_delete) {
/* Empty keep-set + scan I/O error must not delete the whole destination
(the source may not be genuinely empty -- see send_files). */
bool empty_io;
mtx_lock(&context->mutex_scanner);
empty_io = context->scan_had_io_error && context->manifest && context->manifest->size == 0;
mtx_unlock(&context->mutex_scanner);
if (empty_io) {
log_message(LOG_LEVEL_ERROR,
"source scan hit an I/O error before finding any file; refusing to delete "
"with an empty keep-set (--delete)");
goto send_fail;
}
if (send_delete_manifest(client->file_descriptor, context->manifest,
context->excluded_paths) != 0)
goto send_fail;
@@ -1171,6 +1188,11 @@ static int scan_directory_multithreaded(void* pipeline_context) {
break;
}
}
/* Capture the scanner results BEFORE destroying the scanner objects (the
io_error flag lives on the scanner, so reading it after destroy would be a
use-after-free). */
bool had_io =
dirs_mode ? directory_scanner_had_io_error(dscanner) : parallel_scanner_had_io_error(scanner);
if (dirs_mode)
directory_scanner_destroy(dscanner);
else
@@ -1188,8 +1210,6 @@ static int scan_directory_multithreaded(void* pipeline_context) {
}
/* --ignore-errors: an unreadable subdirectory was skipped (workers recorded
io_error, not failure); the deletion still runs but the run reports it. */
bool had_io =
dirs_mode ? directory_scanner_had_io_error(dscanner) : parallel_scanner_had_io_error(scanner);
if (had_io) {
mtx_lock(&context->mutex_scanner);
context->scan_had_io_error = true;
@@ -1360,8 +1380,21 @@ int send_files(Config* config) {
goto send_fail;
bool prescan_ok = scan_paths_only(config, &prepared.options, early_manifest, &had_scan_io);
bool early_ok = false;
if (prescan_ok)
early_ok = send_delete_manifest_early(client, early_manifest, excluded);
if (prescan_ok) {
/* A scan that hit an I/O error and produced NO keep entries is ambiguous
(the source may not be genuinely empty -- part of it was unreadable),
and an empty keep-set would delete the whole destination. Refuse to
delete; the genuine-empty-source case has no io_error and still sends
its (empty) keep-set. */
if (had_scan_io && early_manifest->size == 0) {
log_message(LOG_LEVEL_ERROR,
"source scan hit an I/O error before finding any file; refusing to delete "
"with an empty keep-set (--delete)");
prescan_ok = false;
} else {
early_ok = send_delete_manifest_early(client, early_manifest, excluded);
}
}
array_list_delete(early_manifest);
/* The keep-set (and its protected prefixes) are already on the wire; the
data pass must not append to the exclusion list again. */
@@ -1436,6 +1469,15 @@ int send_files(Config* config) {
goto send_fail;
if (directory_scanner_had_io_error(scanner))
had_scan_io = true;
if (had_scan_io && manifest && manifest->size == 0) {
/* A scan that hit an I/O error and produced no keep entries is ambiguous;
an empty keep-set would delete the whole destination. Refuse to delete
(see the early-timing comment above). */
log_message(LOG_LEVEL_ERROR,
"source scan hit an I/O error before finding any file; refusing to delete with "
"an empty keep-set (--delete)");
goto send_fail;
}
if (manifest) {
/* Late (commit) ordering: all file data is out; transmit the keep-set
manifest so the receiver deletes only after the transfer succeeds. */
@@ -1562,6 +1604,14 @@ int send_files_multithreaded(Config** config_ptr) {
bool prebuilt = prepared_ok && scan_paths_only(config, &prepared.options, context->manifest,
&context->scan_had_io_error);
prepared_scanner_destroy(&prepared);
if (prebuilt && context->scan_had_io_error && context->manifest->size == 0) {
/* Empty keep-set + scan I/O error: refusing an empty keep-set manifest
would have deleted the whole destination (see send_files). */
log_message(LOG_LEVEL_ERROR,
"source scan hit an I/O error before finding any file; refusing to delete "
"with an empty keep-set (--delete)");
prebuilt = false;
}
if (!prebuilt) {
pipeline_context_sender_destroy(context);
return 1;