From 1de0a711db9b0656733789df44c7bc4e4ddfc9fd Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Thu, 14 May 2026 13:11:49 -0500 Subject: [PATCH] refint: Fix segfault in check_foreign_key(). When an UPDATE statement triggers check_foreign_key() with the action set to "cascade", it generates more UPDATE statements to modify the key values in referencing relations. If a new key value is NULL, SPI_getvalue() returns a NULL pointer, which is subsequently passed to quote_literal_cstr(), causing a segfault. To fix, skip quoting when a new key value is NULL and insert an unquoted NULL keyword instead. Oversight in commit 260e97733b. While the refint documentation recommends marking primary key columns NOT NULL, the aforementioned scenario accidentally worked on platforms where snprintf() substitutes "(null)" for NULL pointers. Note that for character-type columns, the old code quoted "(null)" as a string literal, so this didn't always produce correct results. But it still seems better to fix this than to reject cases that previously worked. Reported-by: Nikita Kalinin Author: Ayush Tiwari Reviewed-by: Pierre Forstmann Discussion: https://postgr.es/m/19476-bd04ea6241345303%40postgresql.org Backpatch-through: 14 --- contrib/spi/refint.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/contrib/spi/refint.c b/contrib/spi/refint.c index cbef463230a..413411c173d 100644 --- a/contrib/spi/refint.c +++ b/contrib/spi/refint.c @@ -480,7 +480,8 @@ check_foreign_key(PG_FUNCTION_ARGS) nv = SPI_getvalue(newtuple, tupdesc, fn); appendStringInfo(&sql, " %s = %s ", - args2[k], quote_literal_cstr(nv)); + args2[k], + nv ? quote_literal_cstr(nv) : "NULL"); if (k < nkeys) appendStringInfoString(&sql, ", "); }