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maccess: always use strict semantics for probe_kernel_read

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Except for historical confusion in the kprobes/uprobes and bpf tracers,
which has been fixed now, there is no good reason to ever allow user
memory accesses from probe_kernel_read.  Switch probe_kernel_read to only
read from kernel memory.

[akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig
2020-06-08 21:34:50 -07:00
committed by Linus Torvalds
parent 7676fbf21b
commit 98a23609b1
8 changed files with 19 additions and 54 deletions
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2
kernel/trace/bpf_trace.c
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@@ -196,7 +196,7 @@ bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr)
if (unlikely(ret < 0))
goto fail;
ret = probe_kernel_read_strict(dst, unsafe_ptr, size);
ret = probe_kernel_read(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
goto fail;
return ret;