From: Tom Lane Date: Sat, 6 Jul 2019 15:25:37 +0000 (-0400) Subject: In pg_log_generic(), be more paranoid about preserving errno. X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fb30c9c1c5c36989d6b93906986358cb96936d64;p=postgresql In pg_log_generic(), be more paranoid about preserving errno. This code failed to account for the possibility that malloc() would change errno, resulting in wrong output for %m, not to mention the possibility of message truncation. Such a change is obviously expected when malloc fails, but there's reason to fear that on some platforms even a successful malloc call can modify errno. Discussion: https://postgr.es/m/2576.1527382833@sss.pgh.pa.us --- diff --git a/src/common/logging.c b/src/common/logging.c index f247554a32..895da7150e 100644 --- a/src/common/logging.c +++ b/src/common/logging.c @@ -216,6 +216,8 @@ pg_log_generic_v(enum pg_log_level level, const char *pg_restrict fmt, va_list a buf = pg_malloc_extended(required_len, MCXT_ALLOC_NO_OOM); + errno = save_errno; /* malloc might change errno */ + if (!buf) { /* memory trouble, just print what we can and get out of here */