111 lines
3.2 KiB
Diff
111 lines
3.2 KiB
Diff
From e1f2559efad5e2733ded804f9f1ba8acd8c4de61 Mon Sep 17 00:00:00 2001
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From: Michal Ruprich <michalruprich@gmail.com>
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Date: Tue, 14 Jul 2026 16:35:42 +0200
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Subject: [PATCH] Moving async signal unsafe functions out of signal handler
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There is a very rare race condition in function redirect_output_signal().
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If SIGHUP is received while wget is in malloc() function and a new
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logfile is opened with fopen, another malloc() is called. malloc() is
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not an async signal safe function and should not be called from within a
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signal handler.
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* src/main.c (redirect_output_signal): do not call redirect_output(),
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add an atomic flag.
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* src/log.c (check_redirect_output): move redirect_output() here since this
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is not in a signal handler
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Copyright-paperwork-exempt: Yes
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---
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src/log.c | 26 ++++++++++++++++++++++++++
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src/main.c | 21 ++++++++-------------
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2 files changed, 34 insertions(+), 13 deletions(-)
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diff --git a/src/log.c b/src/log.c
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index fe8c3982..17511327 100644
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--- a/src/log.c
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+++ b/src/log.c
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@@ -37,11 +37,16 @@ as that of the covered work. */
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#include <unistd.h>
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#include <assert.h>
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#include <errno.h>
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+#include <signal.h>
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#include "utils.h"
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#include "exits.h"
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#include "log.h"
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+#if defined(SIGHUP) || defined(SIGUSR1)
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+extern volatile sig_atomic_t redirect_output_sig;
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+#endif
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+
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/* 2005-10-25 SMS.
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VMS log files are often VFC record format, not stream, so fputs() can
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produce multiple records, even when there's no newline terminator in
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@@ -973,6 +978,27 @@ static void
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check_redirect_output (void)
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{
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#if !defined(WINDOWS) && !defined(__VMS)
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+#if defined(SIGHUP) || defined(SIGUSR1)
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+ {
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+ int sig = redirect_output_sig;
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+ if (sig)
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+ {
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+ redirect_output_sig = 0;
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+ const char *signal_name = "WTF?!";
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+#ifdef SIGHUP
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+ if (sig == SIGHUP)
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+ signal_name = "SIGHUP";
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+#endif
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+#ifdef SIGUSR1
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+ if (sig == SIGUSR1)
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+ signal_name = "SIGUSR1";
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+#endif
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+ redirect_output (true, signal_name);
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+ return;
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+ }
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+ }
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+#endif /* defined(SIGHUP) || defined(SIGUSR1) */
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+
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/* If it was redirected already to log file by SIGHUP, SIGUSR1 or -o parameter,
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* it was permanent.
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* If there was no SIGHUP or SIGUSR1 and shell is interactive
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diff --git a/src/main.c b/src/main.c
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index a10a17f3..3926f501 100644
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--- a/src/main.c
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+++ b/src/main.c
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@@ -123,23 +123,18 @@ int numurls = 0;
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#if defined(SIGHUP) || defined(SIGUSR1)
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/* Hangup signal handler. When wget receives SIGHUP or SIGUSR1, it
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will proceed operation as usual, trying to write into a log file.
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- If that is impossible, the output will be turned off. */
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+ If that is impossible, the output will be turned off.
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+
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+ Only async-signal-safe operations are performed here. The actual
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+ redirect (which needs malloc/fopen) is deferred to
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+ check_redirect_output(), called from the logging functions. */
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+
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+volatile sig_atomic_t redirect_output_sig = 0;
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static void
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redirect_output_signal (int sig)
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{
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- const char *signal_name = "WTF?!";
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-
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-#ifdef SIGHUP
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- if (sig == SIGHUP)
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- signal_name = "SIGHUP";
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-#endif
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-#ifdef SIGUSR1
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- if (sig == SIGUSR1)
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- signal_name = "SIGUSR1";
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-#endif
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-
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- redirect_output (true,signal_name);
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+ redirect_output_sig = sig;
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progress_schedule_redirect ();
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signal (sig, redirect_output_signal);
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}
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--
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GitLab
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