From: Willy Tarreau <w@1wt.eu>
Date: Fri, 4 Apr 2025 14:56:44 +0000 (+0200)
Subject: MINOR: tools: also protect the library name resolution against concurrent accesses
X-Git-Tag: v3.2-dev11~23
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8d0c6336778fed316a174fd278c78a88f7dd6975;p=thirdparty%2Fhaproxy.git

MINOR: tools: also protect the library name resolution against concurrent accesses

This is an extension of eb41d768f ("MINOR: tools: use only opportunistic
symbols resolution"). It also makes sure we're not calling dladddr() in
parallel to dladdr_and_size(), as a preventive measure against some
potential deadlocks in the inner layers of the libc.
---

diff --git a/src/tools.c b/src/tools.c
index 2e4858854..b0b066a1d 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -5611,11 +5611,12 @@ const void *resolve_sym_name(struct buffer *buf, const char *pfx, const void *ad
 		goto use_array;
 
 	i = dladdr_and_size(addr, &dli, &size);
-	if (!isolated)
-		HA_SPIN_UNLOCK(OTHER_LOCK, &dladdr_lock);
 
-	if (!i)
+	if (!i) {
+		if (!isolated)
+			HA_SPIN_UNLOCK(OTHER_LOCK, &dladdr_lock);
 		goto use_array;
+	}
 
 	/* 1. prefix the library name if it's not the same object as the one
 	 * that contains the main function. The name is picked between last '/'
@@ -5637,6 +5638,9 @@ const void *resolve_sym_name(struct buffer *buf, const char *pfx, const void *ad
 		ha_thread_relax();
 	}
 
+	if (!isolated)
+		HA_SPIN_UNLOCK(OTHER_LOCK, &dladdr_lock);
+
 	if (dli_main.dli_fbase != dli.dli_fbase) {
 		fname = dli.dli_fname;
 		p = strrchr(fname, '/');