postgres.git / summary / log / commit / refs

commit    77b2d18e9c3b1d42576cfb8c46c25592eb908780
Author:   Nathan Bossart <nathan@postgresql.org>
Date:     Thu May 14 18:11:49 2026 +0000

    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 <n.kalinin@postgrespro.ru>
    Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
    Reviewed-by: Pierre Forstmann <pierre.forstmann@gmail.com>
    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 2733e807046..2fa96fe092b 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, ", ");
 					}


[parent: f18fcd9a450b]