BUG/MINOR: errors: reset diagnostic buffers after thread cleanup

A live worker frees its thread-local diagnostic buffers before EXTRA_OBJS
teardown, whose deinitializers can still emit diagnostics.

ha_free() releases the allocation and clears only the area pointer. It
leaves size, head and data unchanged, while b_is_null() tests size rather
than area. A previously allocated buffer therefore still looks allocated
with a NULL area. Later diagnostics skip lazy allocation and can crash
when accessing the buffer.

Reset both usermsgs_buf and usermsgs_ctx.str to BUF_NULL after freeing
their areas. This clears the stale size and contents metadata so later
diagnostics can allocate fresh buffers. The post-deinit cleanup releases
any buffers reallocated during EXTRA_OBJS teardown.

This could be backported in every maintained versions.

diff --git a/src/errors.c b/src/errors.c
index 934891ee3b4c8a00817a8354bf726cc597c764de..5f55ac9d7d3809ddb77319f08aa48f5ab899d734 100644 (file)
--- a/src/errors.c
+++ b/src/errors.c
@@ -459,6 +459,9 @@ static void deinit_errors_buffers()
        ring_free(_HA_ATOMIC_XCHG(&startup_logs, NULL));
        ha_free(&usermsgs_buf.area);
        ha_free(&usermsgs_ctx.str.area);
+       /* Ensure b_is_null() recognizes the freed buffers. */
+       usermsgs_buf = BUF_NULL;
+       usermsgs_ctx.str = BUF_NULL;
 }
 
 /* errors might be used in threads and even before forking, thus 2 deinit */