perf/core: Exit early on perf_mmap() fail

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: 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.

References

• https://git.kernel.org/stable/c/5ffda7f3ed76ec8defc19d985e33b3b82ba07839
• https://git.kernel.org/stable/c/9b90a48c7de828a15c7a4fc565d46999c6e22d6b
• https://git.kernel.org/stable/c/de85e72598d89880a02170a1cbc27b35a7d978a9
• https://git.kernel.org/stable/c/27d44145bd576bbef9bf6165bcd78128ec3e6cbd
• https://git.kernel.org/stable/c/f41e9eba77bf97626e04296dc5677d02816d2432
• https://git.kernel.org/stable/c/92043120a2e992800580855498ab8507e1b22db9
• https://git.kernel.org/stable/c/163b0d1a209fe0df5476c1df2330ca12b55abf92
• https://git.kernel.org/stable/c/7ff8521f30c4c2fcd4e88bd7640486602bf8a650
• https://git.kernel.org/stable/c/07091aade394f690e7b655578140ef84d0e8d7b0