import fuchsia: check bounds to handle truncated traces

the last record might be partially written so it's important to
check bounds and dump the last record if that happens.
This commit is contained in:
Simon Cruanes 2024-01-08 16:02:17 -05:00
parent 747a3cdea2
commit dff6ea5821
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@ -3,6 +3,7 @@
#include <cstdint> #include <cstdint>
#include <exception> #include <exception>
#include <ostream> #include <ostream>
#include <utility>
#include <vector> #include <vector>
#ifdef _WIN32 #ifdef _WIN32
#include <windows.h> #include <windows.h>
@ -70,7 +71,6 @@ struct PidTidEncoder {
// A span into the main buffer // A span into the main buffer
struct Record { struct Record {
const uint64_t *p; const uint64_t *p;
;
uint16_t len_word; uint16_t len_word;
uint64_t header; uint64_t header;
}; };
@ -171,13 +171,26 @@ std::vector<uint8_t> read_input(const char *input) {
return buf; return buf;
} }
// read next record starting at `offset` // read next record starting at `offset`. Returns
Record read_next_record(std::vector<uint8_t> const &input, size_t &offset) { // either `(ok, r)` for an in-bound record, or `(false, …)` otherwise.
std::pair<bool, Record> read_next_record(std::vector<uint8_t> const &input, size_t &offset) {
// bound check
#define CHECK_BOUND(n) if ((n) > input.size()) { \
fprintf(stderr, "warning: invalid record at offset %" PRIu64 "\n", offset); \
return std::make_pair(false,Record{}); \
}
CHECK_BOUND(offset+8);
uint64_t header = *((uint64_t *)&input[offset]); uint64_t header = *((uint64_t *)&input[offset]);
uint16_t len_word = (header >> 4) & 0xfff; uint16_t len_word = (header >> 4) & 0xfff;
Record sp{(uint64_t *)&input[offset], len_word, header};
CHECK_BOUND(offset + 8*len_word);
Record r{(uint64_t *)&input[offset], len_word, header};
offset += 8 * len_word; offset += 8 * len_word;
return sp; return std::make_pair(true, r);
} }
// there might be multiple processes so we allocate a pseudo-tid // there might be multiple processes so we allocate a pseudo-tid
@ -398,7 +411,8 @@ int main(int argc, char **argv) {
#define CHECK_INIT() if (!initialized) throw TraceNotInitialized{} #define CHECK_INIT() if (!initialized) throw TraceNotInitialized{}
while (offset < buf.size()) { while (offset < buf.size()) {
Record r = read_next_record(buf, offset); auto [ok, r] = read_next_record(buf, offset);
if (!ok) break;
n_records++; n_records++;
uint8_t ty = r.header & 0xf; uint8_t ty = r.header & 0xf;