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Re: Assistance Required: Timeout or Buffer Overflow Issue in PostgreSQL Client Application

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Hi,

Please find the complete stack trace, the language is C and thread here was just performing the operation of fetching records from the postgresDB using SQL_get_tpf_rw() function for which I've also attached implementation here as well

Stack trace of thread 966070:

                                                             #0  0x00000000f7ee1129 __kernel_vsyscall (linux-gate.so.1)

                                                             #1  0x00000000f6ba23b7 __poll (libc.so.6)

                                                             #2  0x00000000f792e5b5 __interceptor_poll (libasan.so.8)

                                                             #3  0x00000000f72b30a8 pqSocketCheck (libpq.so.5)

                                                             #4  0x00000000f72b3864 pqWaitTimed (libpq.so.5)

                                                             #5  0x00000000f72b38d2 pqWait (libpq.so.5)

                                                             #6  0x00000000f72aff03 PQgetResult (libpq.so.5)

                                                             #7  0x00000000f72b036a PQexecFinish (libpq.so.5)

                                                             #8  0x0000000008106dd4 checkLOCK (server)

                                                             #9  0x000000000811d871 SQL_get_tpf_rw (server)

                                                             #10 0x0000000008180269 get_tpf_rw (server)

                                                             #11 0x0000000008189e47 FINDC (server)

                                                             #12 0x000000000818cd20 FINWC (server)

                                                             #13 0x00000000f2d03778 _segKIP8 (kip8.so)

                                                             #14 0x000000000816ad0e call_segment (server)

                                                             #15 0x000000000816ba0b ENTRC (server)

                                                             #16 0x00000000f2d096ee _segKIP5 (kip5.so)

                                                             #17 0x000000000816ad0e call_segment (server)

                                                             #18 0x000000000816ba0b ENTRC (server)

                                                             #19 0x00000000f2d1722d _segKIP4 (kip4.so)

                                                             #20 0x000000000816ad0e call_segment (server)

                                                             #21 0x000000000816ba0b ENTRC (server)

                                                             #22 0x00000000f2d1dee1 _segKIPB (kipb.so)

                                                             #23 0x000000000816ad0e call_segment (server)

                                                             #24 0x000000000816c454 ENTNC (server)

                                                             #25 0x00000000f2d2be54 _segKIP9 (kip9.so)

                                                             #26 0x000000000816ad0e call_segment (server)

                                                             #27 0x00000000081c264d call_appl_entry (server)

                                                             #28 0x000000000807f227 extest (server)

                                                             #29 0x000000000808923f handle_COMMS_TYPE_FUNCTIONAL_MESSAGE (server)

                                                             #30 0x000000000808d849 handle_comms_message (server)

                                                             #31 0x00000000f77d6e41 worker (libuv.so.1)

                                                             #32 0x00000000f78ff67a _ZL17asan_thread_startPv (libasan.so.8)

                                                             #33 0x00000000f6b170ad start_thread (libc.so.6)

                                                             #34 0x00000000f6bb1dea __clone (libc.so.6)

Regards,
Sasmit Utkarsh
+91-7674022625


On Thu, Oct 24, 2024 at 9:47 PM Igor Korot <ikorot01@xxxxxxxxx> wrote:
Hi,
Is this a complete backtrace?
Can you post a complete backtrace? We need to see if there is a reference
to your application code?

What language is it written in?
What operation this thread was performing?

Thank you.

On Thu, Oct 24, 2024 at 11:12 AM Sasmit Utkarsh <utkarshsasmit@xxxxxxxxx> wrote:
>
> Dear PostgreSQL Community Team,
>
> I hope this message finds you well. I am reaching out for assistance with an issue encountered in our application, which communicates with PostgreSQL using the libpq client library.
>
> Issue Details:
> We have observed a problem where one of the application's threads gets stuck during a database operation. Below is a stack trace of the affected thread:
>
> Application Logs:
> Oct 23 10:08:44.806235 cucmtpccu1 shc-server@2.service[966034]: 0966070{ef5f81a7-d35b-4604-953d-a35665e505b7.010000}KIP8-SQL_get_tpf_rw()-SQL read data from File Address before lock fa(-1810606079) fa(94145801) fa2 htonl(22549652)
> Oct 23 10:08:44.806235 cucmtpccu1 shc-server@2.service[966034]: 0966070{ef5f81a7-d35b-4604-953d-a35665e505b7.010000}KIP8-SQL_get_tpf_rw() SelectDataCommand = CALL SQL_select_data_procedure($1, $2, NULL, NULL) hold(0) fa(-1810606079)
> Oct 23 10:08:44.807814 cucmtpccu1 shc-server@2.service[966034]: *** buffer overflow detected ***: terminated
>
> Stack Trace of Thread 966070:
> #0  0x00000000f7ee1129 __kernel_vsyscall (linux-gate.so.1)
> #1  0x00000000f6ba23b7 __poll (libc.so.6)
> #2  0x00000000f792e5b5 __interceptor_poll (libasan.so.8)
> #3  0x00000000f72b30a8 pqSocketCheck (libpq.so.5)
> #4  0x00000000f72b3864 pqWaitTimed (libpq.so.5)
> #5  0x00000000f72b38d2 pqWait (libpq.so.5)
> #6  0x00000000f72aff03 PQgetResult (libpq.so.5)
> #7  0x00000000f72b036a PQexecFinish (libpq.so.5)
> #8  0x0000000008106dd4 checkLOCK (server)
> #9  0x000000000811d871 SQL_get_tpf_rw (server)
> ...
>
> The stack trace shows that the thread is stuck in a poll operation while waiting for socket activity within the PostgreSQL client library (libpq). We suspect this could be related to a network timeout or issue. However, the application logs indicate a buffer overflow before the crash, which raises questions about whether these are related.
>
> Questions:
> -Could the buffer overflow be causing the crash, and if so, how is it related to the socket activity?
> -Are there specific configurations or checks we should perform to diagnose this issue further?
> -Any suggestions for possible solutions to resolve this problem?
>
> For additional context, I've verified that the specified record does exist in the database, and I am also attaching the implementation details for the checkLOCK function corresponding to the stack trace.
>
> Please let me know if you need any more details
>
> Your assistance with troubleshooting this would be highly appreciated.
>
> Regards,
> Sasmit Utkarsh
> +91-7674022625
int get_tpf_rw( int32_t fa, unsigned char **core_blk, size_t *st_size, unsigned char *bid, unsigned char *rcc, int *fd, bool hold, unsigned char **mmap_ptr)
{
  if(sql_db == 1)//  {
     return SQL_get_tpf_rw(fa, core_blk, st_size, bid, rcc, fd, hold, mmap_ptr );
  // }  else //if(sql_db == 0)
  return FILE_get_tpf_rw(fa, core_blk, st_size, bid, rcc, fd, hold, mmap_ptr );
}

int SQL_get_tpf_rw( int32_t fa, unsigned char **core_blk, size_t *st_size, unsigned char *bid, unsigned char *rcc, int *fd, bool hold, unsigned char **mmap_ptr)
{
char *p;
char *c;
int rc;
struct stat statbuf;

PGresult *res=NULL;
uint32_t fa2 = htonl(fa);
char *fa_val = (char *)&fa2;
bool hold2 = hold;
char *hold_val = (char *)&hold2;


const char *paramValues[2]  	= {fa_val, hold_val};
int   paramLengths[2]       	= {sizeof(fa2), sizeof(hold2)};
int   paramFormats[2]       	= {1, 1};       // identify parameter as binary

if(SQL_vsn10) {
	paramValues[0]  	= fa_val;
	paramValues[1]  	= NULL; 
	paramLengths[0]       	= sizeof(fa2);
	paramLengths[1]       	= 0; 
	paramFormats[0]       	= 1;  
	paramFormats[1]       	= 0; 
}
/**
if(shadowSQL_vsn10) {
        paramValues[0]          = fa_val;
        paramValues[1]          = NULL;
        paramLengths[0]         = sizeof(fa2);
        paramLengths[1]         = 0;
        paramFormats[0]         = 1;
        paramFormats[1]         = 0;
}
**/
int   resultFormat          	= 1;		// binary 
int   nFields = 0;
int   nTuples = 0;
int   blk_size = 0;
char *blk_size_val;
char *data_val;

	if(bid)
	{
		LOG_TRACE("%s() SQL read data from File Address fa(%i) fa(%08X) fa2 htonl(%i) bid (%02X%02X)",__func__,fa,fa,fa2,*bid,*(bid+1));
	}
	else
	{
		LOG_TRACE("%s() SQL read data from File Address fa(%i) fa(%08X) fa2 htonl(%i) bid (0)",__func__,fa,fa,fa2);
	}

        LOG_DEBUG("%s()-SQL read data from File Address before lock fa(%i) fa(%08X) fa2 htonl(%i)",__func__,fa,fa,fa2); 

	//LOG_DEBUG("%s() CALL SQL_select_data_procedure1(%i, %i, NULL);",__func__,fa2,hold2);
        //LOG_DEBUG("%s() SELECT data FROM fs_data WHERE file_address = %i","SQL_select_data_procedure1",fa2);

        bool is_data_found = false;
        if(is_shadow_db)
        {
            LOG_DEBUG("%s() shadowSelectDataCommand = %s hold(%i) fa(%i)",__func__,shadowSelectDataCommand,hold,fa);
            LOG_DEBUG("%s() shadowSelectDataNParams = %i",__func__,shadowSelectDataNParams);
        }
        else
        {
	    LOG_DEBUG("%s() SelectDataCommand = %s hold(%i) fa(%i)",__func__,SelectDataCommand,hold,fa);
	    LOG_DEBUG("%s() SelectDataNParams = %i",__func__,SelectDataNParams);
        }
	checkLOCK(fa);
	if(is_shadow_db) 
	{
		res = PQexecPrepared(shadow_db_conn,
				     shadowSelectDataName,
				     shadowSelectDataNParams,
				     paramValues,
				     paramLengths,
				     paramFormats,
				     resultFormat);
                LOG_DEBUG("%s()- check now in shadow db for fa(%i) fa(%08X) PQresultStatus(res):%s",__func__,fa,fa,PQresStatus(PQresultStatus(res)));
                if (PQresultStatus(res) == PGRES_TUPLES_OK)
		{
                    nTuples = PQntuples(res);       // number of rows

                    if(nTuples == 0)
                    {
                       LOG_DEBUG("fa(%i) fa(%08X) could not be retrieved from Shadow DB so look into base db",fa,fa);
                    }
                    else
                    {
                       blk_size_val = PQgetvalue(res, 0, 0);
                       data_val = PQgetvalue(res, 0, 1);
                       if( data_val != NULL && *data_val != '\0')
                       {
                          is_data_found = true;
                          LOG_DEBUG("fa(%i) fa(%08X) retrieved successfully from Shadow DB",fa,fa);
                       }
                    }
                }
                else
                    LOG_ERROR("SELECT failed on Shadow DB: %s", PQerrorMessage(shadow_db_conn ));

                if (!is_data_found) {
                      PQclear(res);  // Cleared result only if we are moving to main DB query
                }
	}
	if(is_data_found !=true) 
	{
	        res = PQexecPrepared(conn,
			     SelectDataName,
			     SelectDataNParams,
			     paramValues,
			     paramLengths,
			     paramFormats,
			     resultFormat);
        }
	LOG_DEBUG("%s() res = %s",__func__,PQresStatus(PQresultStatus(res)));

	if ( hold )
	{
		if ( SQL_vsn10 )
		{
			SQL_lock_row(fa);
		}
                LOG_DEBUG("%s()-SQL read data from File Address- locked fa(%i) fa(%08X) fa2 htonl(%i)",__func__,fa,fa,fa2);
	}
	checkLOCK(fa);

    if (PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        LOG_ERROR("SELECT failed: %s", PQerrorMessage(conn));
		LOG_DEBUG("ROLLBACK TRANSACTION AND CHAIN");
        PQclear(res);
		res = PQexec(conn,"ROLLBACK TRANSACTION AND CHAIN");
		LOG_ERROR("INVALID_FILE_ADDRESS %08X",fa);
		rc = ERR_INVALID_FILE_ADDRESS;
		if ( ((uint32_t)fa)>>24 != 0x94) {
			if (COUNT < 255) {

				if ( bid != NULL ) {
					LOG_INFO("missing data: %08x %02x %02x", fa, *bid,*(bid+1));
					char str1[8];
					int16_t a=*bid;
					int16_t b=*(bid+1);
					sprintf(str1,"%02x%02x",a,b);
					FA[COUNT]=fa;
					memcpy(REC_ID1[COUNT],str1,5);
					COUNT++;
				} else {
					bid=0x0000;
					LOG_INFO("missing data: %08x", fa);
					FA[COUNT++]=fa;
					REC_ID1[COUNT][0]=0x00;
				}
			}
		}
		PQclear(res);
    }
	else
	{
		nFields = PQnfields(res);	// number of columns
		nTuples = PQntuples(res);	// number of rows
		LOG_DEBUG("%s() nFields(cols)=%i nTuples(rows)=%i",__func__,nFields,nTuples);
		if( nFields == 0 || nTuples == 0) 
		{
                	LOG_ERROR("SELECT failed: NO ROWS RETURNED");
                        PQclear(res);
			res = PQexec(conn,"ROLLBACK TRANSACTION AND CHAIN");
			LOG_ERROR("INVALID_FILE_ADDRESS %08X",fa);
			rc = ERR_INVALID_FILE_ADDRESS;
			if ( ((uint32_t)fa)>>24 != 0x94) {
				if (COUNT < 255) {
					if ( bid != NULL ) {
						LOG_INFO("missing data: %08x %02x %02x", fa, *bid,*(bid+1));
						char str1[8];
						int16_t a=*bid;
						int16_t b=*(bid+1);
						sprintf(str1,"%02x%02x",a,b);
						FA[COUNT]=fa;
						memcpy(REC_ID1[COUNT],str1,5);
						COUNT++;
					} else {
						bid=0x0000;
						LOG_INFO("missing data: %08x", fa);
						FA[COUNT++]=fa;
						REC_ID1[COUNT][0]=0x00;
					}
				}
			}
			PQclear(res);
		}
		else
		{
			blk_size = ntohl(*(uint32_t *)PQgetvalue (res, 0, 0));
			LOG_DEBUG("%s() blk_size returned is %i",__func__,blk_size);
			if(blk_size < 127 || blk_size > 4096)
			{
                		LOG_ERROR("SELECT failed: NO ROWS RETURNED");
                                PQclear(res);
				res = PQexec(conn,"ROLLBACK TRANSACTION AND CHAIN");
				LOG_ERROR("INVALID_FILE_ADDRESS %08X",fa);
				rc = ERR_INVALID_FILE_ADDRESS;
				if ( ((uint32_t)fa)>>24 != 0x94) {
					if (COUNT < 255) {
						if ( bid != NULL ) {
							LOG_INFO("missing data: %08x %02x %02x", fa, *bid,*(bid+1));
							char str1[8];
							int16_t a=*bid;
							int16_t b=*(bid+1);
							sprintf(str1,"%02x%02x",a,b);
							FA[COUNT]=fa;
							memcpy(REC_ID1[COUNT],str1,5);
							COUNT++;
						} else {
							bid=0x0000;
							LOG_INFO("missing data: %08x", fa);
							FA[COUNT++]=fa;
							REC_ID1[COUNT][0]=0x00;
						}
					}
				}
				PQclear(res);
			}
			else
			{
				*fd = fa;				// use File Address as File Descriptor 
				c = PQgetvalue(res, 0, 1);  		// SELECT has data as second field 
				//dump_hex(c,16);
				//printf(" PQgetlength of data  = %i\n",PQgetlength(res,0,1));
				p = c;	// use same pointer for both mmap and core_blk
	
				LOG_DEBUG("Core block address %p for FA %08X (RW)", p, fa);
		                dump_hex(p,32);
				/* probably need some validation of block size? */
				if (bid != NULL && memcmp(bid, p, 2) != 0 && memcmp(bid, "\x00\x00", 2) != 0) {
					rc = ERR_RID_MISMATCH;
					int b1 = *(unsigned char *)p;
					int b2 = *(unsigned char *)(p+1);
					int a1 = *(unsigned char *)(bid);
					int a2 = *(unsigned char *)(bid+1);
					LOG_ERROR("Error record id mismatch %02X%02X != %02X%02X FA %08X", b1, b2, a1, a2, fa);
				} else if (rcc != NULL && *rcc != 0 && memcmp(rcc, p+2, 1) != 0) {
					rc = ERR_RCC_MISMATCH;
					int b1 = *(unsigned char *)(p+2);
					int a1 = *(unsigned char *)(rcc);
					LOG_ERROR("Error rcc mismatch %02X != %02X FA %08X", b1, a1, fa);
				} else {
					rc = 0;
				}

                                *core_blk = (unsigned char *)malloc(blk_size);
                                if (*core_blk == NULL) {
                                    LOG_ERROR("Memory allocation failed");
                                    PQclear(res);  
                                    return ERR_IO_HARDWARE_ERROR;
                                }
                                memcpy(*core_blk,c , blk_size);
				LOG_TRACE("Core block address %p and mmap_ptr %p for FA %08X (RW)", core_blk, mmap_ptr,fa);

				//*mmap_ptr = c;
				//*core_blk = p;
				*st_size = blk_size;
                                PQclear(res);
                                LOG_DEBUG("%s: cleared the result from query in the end",__func__);
				//dump_hex(*mmap_ptr,1055);
			}
		}
	}
	//LOG_DEBUG("%s() rc = %i",__func__,rc);
	return rc;
}

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