postgres.git / summary / log / commit / refs
commit 8e33fb9ef1df7f1a1e7ef2fe0dbddfff2520f161
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue Mar 14 23:17:31 2023 +0000
First released in: 16.0, 11.20, 12.15, 13.11, 14.8, 15.3
Fix corner case bug in numeric to_char() some more.
The band-aid applied in commit f0bedf3e4 turns out to still need
some work: it made sure we didn't set Np->last_relevant too small
(to the left of the decimal point), but it didn't prevent setting
it too large (off the end of the partially-converted string).
This could result in fetching data beyond the end of the allocated
space, which with very bad luck could cause a SIGSEGV, though
I don't see any hazard of interesting memory disclosure.
Per bug #17839 from Thiago Nunes. The bug's pretty ancient,
so back-patch to all supported versions.
Discussion: https://postgr.es/m/17839-aada50db24d7b0da@postgresql.org
src/backend/utils/adt/formatting.c | 11 +++++++++--
src/test/regress/expected/numeric.out | 6 ++++++
src/test/regress/sql/numeric.sql | 1 +
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 7b1a988b19f..979f55914ea 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -4854,13 +4854,20 @@ NUM_processor(FormatNode *node, NUMDesc *Num, char *inout,
/*
* If any '0' specifiers are present, make sure we don't strip
- * those digits.
+ * those digits. But don't advance last_relevant beyond the last
+ * character of the Np->number string, which is a hazard if the
+ * number got shortened due to precision limitations.
*/
if (Np->last_relevant && Np->Num->zero_end > Np->out_pre_spaces)
{
+ int last_zero_pos;
char *last_zero;
- last_zero = Np->number + (Np->Num->zero_end - Np->out_pre_spaces);
+ /* note that Np->number cannot be zero-length here */
+ last_zero_pos = strlen(Np->number) - 1;
+ last_zero_pos = Min(last_zero_pos,
+ Np->Num->zero_end - Np->out_pre_spaces);
+ last_zero = Np->number + last_zero_pos;
if (Np->last_relevant < last_zero)
Np->last_relevant = last_zero;
}
diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index ced7980709f..6400bcb5254 100644
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -1266,6 +1266,12 @@ SELECT '' AS to_char_26, to_char('100'::numeric, 'FM999');
| 100
(1 row)
+SELECT to_char('12345678901'::float8, 'FM9999999999D9999900000000000000000');
+ to_char
+-----------------
+ ##########.####
+(1 row)
+
-- Check parsing of literal text in a format string
SELECT '' AS to_char_27, to_char('100'::numeric, 'foo999');
to_char_27 | to_char
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index e5ff2b59029..9924419a577 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -799,6 +799,7 @@ SELECT '' AS to_char_23, to_char(val, '9.999EEEE') FROM num_data;
SELECT '' AS to_char_24, to_char('100'::numeric, 'FM999.9');
SELECT '' AS to_char_25, to_char('100'::numeric, 'FM999.');
SELECT '' AS to_char_26, to_char('100'::numeric, 'FM999');
+SELECT to_char('12345678901'::float8, 'FM9999999999D9999900000000000000000');
-- Check parsing of literal text in a format string
SELECT '' AS to_char_27, to_char('100'::numeric, 'foo999');
[parent: 234941a3bbf3]