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Fri, 08 Jan 2021 18:19:33 -0800 (PST) MIME-Version: 1.0 References: <20210108205857.1471269-1-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Fri, 8 Jan 2021 18:19:22 -0800 Message-ID: Subject: Re: [PATCH 1/1] mm/madvise: replace ptrace attach requirement for process_madvise To: David Rientjes Cc: Minchan Kim , Andrew Morton , Jann Horn , Kees Cook , Jeffrey Vander Stoep , Michal Hocko , Shakeel Butt , =?UTF-8?Q?Edgar_Arriaga_Garc=C3=ADa?= , Tim Murray , linux-mm , selinux@vger.kernel.org, Linux API , LKML , kernel-team Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jan 8, 2021 at 5:02 PM David Rientjes wrote: > > On Fri, 8 Jan 2021, Suren Baghdasaryan wrote: > > > > > @@ -1197,12 +1197,22 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > > > > goto release_task; > > > > } > > > > > > > > - mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS); > > > > + /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */ > > > > + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); > > > > if (IS_ERR_OR_NULL(mm)) { > > > > ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; > > > > goto release_task; > > > > } > > > > > > > > + /* > > > > + * Require CAP_SYS_NICE for influencing process performance. Note that > > > > + * only non-destructive hints are currently supported. > > > > + */ > > > > + if (!capable(CAP_SYS_NICE)) { > > > > + ret = -EPERM; > > > > + goto release_task; > > > > > > mmput? > > > > Ouch! Thanks for pointing it out! Will include in the next respin. > > > > With the fix, feel free to add: > > Acked-by: David Rientjes Thanks! Will post a new version with the fix on Monday. > > Thanks Suren!