Re: [PATCH 1/1] mm/madvise: replace ptrace attach requirement for process_madvise

From
Florian Weimer <hidden>
Date
2021-01-11 10:21:38
Also in
linux-mm, lkml, selinux
* Suren Baghdasaryan:
quoted hunk
diff --git a/mm/madvise.c b/mm/madvise.c
index 6a660858784b..c2d600386902 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -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;
 	}
Shouldn't this depend on the requested behavior?  Several operations
directly result in observable changes, and go beyond performance tuning.

Thanks,
Florian
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Thread (3 messages) 3 messages, 2 authors, last reply 2021-01-11
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