database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-29 16:21:20 +03:00
Code

Fix explicit valgrind interaction in read_stream.c.

Browse Source 
This is a back-patch of commits 2a8a0067 and 2509b857 into
REL_17_STABLE.  It's doesn't fix any known live bug in PostgreSQL v17
itself, but an extension could in theory have used the per-buffer data
feature and seen spurious errors under Valgrind.

Discussion: https://postgr.es/m/CA%2BhUKG%2Bg6aXpi2FEHqeLOzE%2BxYw%3DOV%2B-N5jhOEnnV%2BF0USM9xA%40mail.gmail.com
This commit is contained in:
Thomas Munro 2025-02-15 13:13:19 +13:00
parent 29cce279bb
commit 57dca6faa9
1 changed files with 32 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
src/backend/storage/aio/read_stream.c
View File

@ -176,9 +176,20 @@ read_stream_get_block(ReadStream *stream, void *per_buffer_data)
if (blocknum != InvalidBlockNumber) if (blocknum != InvalidBlockNumber)
stream->buffered_blocknum = InvalidBlockNumber; stream->buffered_blocknum = InvalidBlockNumber;
else else
{
/*
* Tell Valgrind that the per-buffer data is undefined. That replaces
* the "noaccess" state that was set when the consumer moved past this
* entry last time around the queue, and should also catch callbacks
* that fail to initialize data that the buffer consumer later
* accesses. On the first go around, it is undefined already.
*/
VALGRIND_MAKE_MEM_UNDEFINED(per_buffer_data,
stream->per_buffer_data_size);
blocknum = stream->callback(stream, blocknum = stream->callback(stream,
stream->callback_private_data, stream->callback_private_data,
per_buffer_data); per_buffer_data);
}
return blocknum; return blocknum;
} }
@ -687,8 +698,11 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data)
} }
#ifdef CLOBBER_FREED_MEMORY #ifdef CLOBBER_FREED_MEMORY
/* Clobber old buffer and per-buffer data for debugging purposes. */ /* Clobber old buffer for debugging purposes. */
stream->buffers[oldest_buffer_index] = InvalidBuffer; stream->buffers[oldest_buffer_index] = InvalidBuffer;
#endif
#if defined(CLOBBER_FREED_MEMORY) || defined(USE_VALGRIND)
/* /*
* The caller will get access to the per-buffer data, until the next call. * The caller will get access to the per-buffer data, until the next call.
@ -697,11 +711,23 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data)
* that is holding a dangling pointer to it. * that is holding a dangling pointer to it.
*/ */
if (stream->per_buffer_data) if (stream->per_buffer_data)
wipe_mem(get_per_buffer_data(stream, {
oldest_buffer_index == 0 ? void *per_buffer_data;
stream->queue_size - 1 :
oldest_buffer_index - 1), per_buffer_data = get_per_buffer_data(stream,
stream->per_buffer_data_size); oldest_buffer_index == 0 ?
stream->queue_size - 1 :
oldest_buffer_index - 1);
#if defined(CLOBBER_FREED_MEMORY)
/* This also tells Valgrind the memory is "noaccess". */
wipe_mem(per_buffer_data, stream->per_buffer_data_size);
#elif defined(USE_VALGRIND)
/* Tell it ourselves. */
VALGRIND_MAKE_MEM_NOACCESS(per_buffer_data,
stream->per_buffer_data_size);
#endif
}
#endif #endif
/* Pin transferred to caller. */ /* Pin transferred to caller. */