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Avoid passing unintended format codes to snprintf().

Browse source 
timeofday() assumed that the output of pg_strftime() could not contain
% signs, other than the one it explicitly asks for with %%.  However,
we don't have that guarantee with respect to the time zone name (%Z).
A crafted time zone setting could abuse the subsequent snprintf()
call, resulting in crashes or disclosure of server memory.

To fix, split the pg_strftime() call into two and then treat the
outputs as literal strings, not a snprintf format string.  The
extra pg_strftime() call doesn't really cost anything, since the
bulk of the conversion work was done by pg_localtime().

Also, adjust buffer widths so that we're not risking string truncation
during the snprintf() step, as that would create a hazard of producing
mis-encoded output.

This also fixes a latent portability issue: the format string expects
an int, but tp.tv_usec is long int on many platforms.

Reported-by: Xint Code
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Backpatch-through: 14
Security: CVE-2026-6474
This commit is contained in:
Tom Lane 2026-05-11 05:13:46 -07:00 committed by Noah Misch
parent 46b4f5c11b
commit 76ab76f875
1 changed files with 9 additions and 5 deletions
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14
src/backend/utils/adt/timestamp.c
View file

@ -1685,15 +1685,19 @@ Datum
timeofday(PG_FUNCTION_ARGS)
{
struct timeval tp;
char templ[128];
char buf[128];
pg_time_t tt;
struct pg_tm *tm;
char part1[128];
char part2[128];
char buf[128 + 128 + 10];
gettimeofday(&tp, NULL);
tt = (pg_time_t) tp.tv_sec;
pg_strftime(templ, sizeof(templ), "%a %b %d %H:%M:%S.%%06d %Y %Z",
pg_localtime(&tt, session_timezone));
snprintf(buf, sizeof(buf), templ, tp.tv_usec);
tm = pg_localtime(&tt, session_timezone);
pg_strftime(part1, sizeof(part1), "%a %b %d %H:%M:%S", tm);
pg_strftime(part2, sizeof(part2), "%Y %Z", tm);
snprintf(buf, sizeof(buf), "%s.%06d %s", part1, (int) tp.tv_usec, part2);
PG_RETURN_TEXT_P(cstring_to_text(buf));
}