perf/core: Exit early on perf_mmap() fail

When perf_mmap() fails to allocate a buffer, it still invokes the
event_mapped() callback of the related event. On X86 this might increase
the perf_rdpmc_allowed reference counter. But nothing undoes this as
perf_mmap_close() is never called in this case, which causes another
reference count leak.

Return early on failure to prevent that.

Fixes: 1e0fb9ec679c ("perf: Add pmu callbacks to track event mapping and unmapping")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: stable@vger.kernel.org

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e89e772285912e51859a8d6a196bde8662e8d989..a2e3591175c6541e2fba86da7b993f3b859cf3cd 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7138,6 +7138,9 @@ aux_unlock:
                mutex_unlock(aux_mutex);
        mutex_unlock(&event->mmap_mutex);
 
+       if (ret)
+               return ret;
+
        /*
         * Since pinned accounting is per vm we cannot allow fork() to copy our
         * vma.
@@ -7145,8 +7148,7 @@ aux_unlock:
        vm_flags_set(vma, VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP);
        vma->vm_ops = &perf_mmap_vmops;
 
-       if (!ret)
-               ret = map_range(rb, vma);
+       ret = map_range(rb, vma);
 
        mapped = get_mapped(event, event_mapped);
        if (mapped)