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commit    9cd0d77dfcdf847cc42e0401d406c501b3baccbb
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Fri Jan 05 11:08:34 2024 +0000
First released in: 17.0, 16.2

    Fix corruption of local buffer state during extend of temp relation
    
    A typo has been introduced by 31966b151e6a when updating the state of a
    local buffer when a temporary relation is extended, for the case of a
    block included in the relation range extended, when it is already found
    in the hash table holding the local buffers.  In this case, BM_VALID
    should be cleared, but the buffer state was changed so as BM_VALID
    remained while clearing the other flags.
    
    As reported on the thread, it was possible to corrupt the state of the
    local buffers on ENOSPC, but the states would be corrupted on any kind
    of ERROR during the relation extend (like partial writes or some other
    errno).
    
    Reported-by: Alexander Lakhin
    Author: Tender Wang
    Reviewed-by: Richard Guo, Alexander Lakhin, Michael Paquier
    Discussion: https://postgr.es/m/18259-6e256429825dd435@postgresql.org
    Backpatch-through: 16


 src/backend/storage/buffer/localbuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 5a195c0d596..1be4f4f8daf 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -380,7 +380,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 			hash_search(LocalBufHash, (void *) &tag, HASH_ENTER, &found);
 		if (found)
 		{
-			BufferDesc *existing_hdr = GetLocalBufferDescriptor(hresult->id);
+			BufferDesc *existing_hdr;
 			uint32		buf_state;
 
 			UnpinLocalBuffer(BufferDescriptorGetBuffer(victim_buf_hdr));
@@ -392,7 +392,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 			buf_state = pg_atomic_read_u32(&existing_hdr->state);
 			Assert(buf_state & BM_TAG_VALID);
 			Assert(!(buf_state & BM_DIRTY));
-			buf_state &= BM_VALID;
+			buf_state &= ~BM_VALID;
 			pg_atomic_unlocked_write_u32(&existing_hdr->state, buf_state);
 		}
 		else


[parent: 9391f71523b6]