diff options
| author | Christoph Hellwig <hch@lst.de> | 2020-06-08 21:34:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-09 09:39:15 -0700 |
| commit | 98a23609b10364a51a1bb3688f8dd1cd1aa94a9a (patch) | |
| tree | 8cf32f92fccd8cd5264434d42fa68dcba4c2ab3c /arch/x86/mm | |
| parent | 7676fbf21b5fa04341c8046c2cbcd1949293e7ec (diff) | |
| download | linux-98a23609b10364a51a1bb3688f8dd1cd1aa94a9a.tar.bz2 | |
maccess: always use strict semantics for probe_kernel_read
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>
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/maccess.c | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index 86000c1150e8..e1d7d7477c22 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -9,13 +9,10 @@ static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits) return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits); } -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) { unsigned long vaddr = (unsigned long)unsafe_src; - if (!strict) - return true; - /* * Range covering the highest possible canonical userspace address * as well as non-canonical address range. For the canonical range @@ -25,10 +22,8 @@ bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr; } #else -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) { - if (!strict) - return true; return (unsigned long)unsafe_src >= TASK_SIZE_MAX; } #endif |