Avoid overflow in size calculations in formatting.c.

A few functions in this file were incautious about multiplying a
possibly large integer by a factor more than 1 and then using it as
an allocation size.  This is harmless on 64-bit systems where we'd
compute a size exceeding MaxAllocSize and then fail, but on 32-bit
systems we could overflow size_t, leading to an undersized
allocation and buffer overrun.  To fix, use palloc_array() or
mul_size() instead of handwritten multiplication.

Reported-by: Sven Klemm <sven@tigerdata.com>
Reported-by: Xint Code
Author: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Tatsuo Ishii <ishii@postgresql.org>
Security: CVE-2026-6473
Backpatch-through: 14

diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 764f386605ccc2ea3aa56f8c0916b2910a1c37d2..7a043719a3d0a616db9344109ecaff7a695f95da 100644 (file)
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -4010,7 +4010,7 @@ datetime_to_char_body(TmToChar *tmtc, text *fmt, bool is_interval, Oid collid)
        /*
         * Allocate workspace for result as C string
         */
-       result = palloc((fmt_len * DCH_MAX_ITEM_SIZ) + 1);
+       result = palloc(mul_size(fmt_len, DCH_MAX_ITEM_SIZ) + 1);
        *result = '\0';
 
        if (fmt_len > DCH_CACHE_SIZE)
@@ -4021,7 +4021,7 @@ datetime_to_char_body(TmToChar *tmtc, text *fmt, bool is_interval, Oid collid)
                 */
                incache = false;
 
-               format = (FormatNode *) palloc((fmt_len + 1) * sizeof(FormatNode));
+               format = palloc_array(FormatNode, fmt_len + 1);
 
                parse_format(format, fmt_str, DCH_keywords,
                                         DCH_suff, DCH_index, DCH_FLAG, NULL);
@@ -4509,7 +4509,7 @@ do_to_timestamp(text *date_txt, text *fmt, Oid collid, bool std,
                         * Allocate new memory if format picture is bigger than static
                         * cache and do not use cache (call parser always)
                         */
-                       format = (FormatNode *) palloc((fmt_len + 1) * sizeof(FormatNode));
+                       format = palloc_array(FormatNode, fmt_len + 1);
 
                        parse_format(format, fmt_str, DCH_keywords, DCH_suff, DCH_index,
                                                 DCH_FLAG | (std ? STD_FLAG : 0), NULL);
@@ -4961,7 +4961,7 @@ NUM_cache(int len, NUMDesc *Num, text *pars_str, bool *shouldFree)
                 * Allocate new memory if format picture is bigger than static cache
                 * and do not use cache (call parser always)
                 */
-               format = (FormatNode *) palloc((len + 1) * sizeof(FormatNode));
+               format = palloc_array(FormatNode, len + 1);
 
                *shouldFree = true;