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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sasha Levin <sashal@kernel.org>, Andrii Nakryiko <andriin@fb.com>,
	Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: [PATCH AUTOSEL 5.6 006/606] bpf: Fix bug in mmap() implementation for BPF array map
Date: Mon,  8 Jun 2020 19:02:11 -0400	[thread overview]
Message-ID: <20200608231211.3363633-6-sashal@kernel.org> (raw)
In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org>

[ Upstream commit 333291ce5055f2039afc907badaf5b66bc1adfdc ]

mmap() subsystem allows user-space application to memory-map region with
initial page offset. This wasn't taken into account in initial implementation
of BPF array memory-mapping. This would result in wrong pages, not taking into
account requested page shift, being memory-mmaped into user-space. This patch
fixes this gap and adds a test for such scenario.

Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200512235925.3817805-1-andriin@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/bpf/arraymap.c                         | 7 ++++++-
 tools/testing/selftests/bpf/prog_tests/mmap.c | 9 +++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 95d77770353c..1d6120fd5ba6 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -486,7 +486,12 @@ static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
 	if (!(map->map_flags & BPF_F_MMAPABLE))
 		return -EINVAL;
 
-	return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), pgoff);
+	if (vma->vm_pgoff * PAGE_SIZE + (vma->vm_end - vma->vm_start) >
+	    PAGE_ALIGN((u64)array->map.max_entries * array->elem_size))
+		return -EINVAL;
+
+	return remap_vmalloc_range(vma, array_map_vmalloc_addr(array),
+				   vma->vm_pgoff + pgoff);
 }
 
 const struct bpf_map_ops array_map_ops = {
diff --git a/tools/testing/selftests/bpf/prog_tests/mmap.c b/tools/testing/selftests/bpf/prog_tests/mmap.c
index 16a814eb4d64..b0e789678aa4 100644
--- a/tools/testing/selftests/bpf/prog_tests/mmap.c
+++ b/tools/testing/selftests/bpf/prog_tests/mmap.c
@@ -197,6 +197,15 @@ void test_mmap(void)
 	CHECK_FAIL(map_data->val[far] != 3 * 321);
 
 	munmap(tmp2, 4 * page_size);
+
+	/* map all 4 pages, but with pg_off=1 page, should fail */
+	tmp1 = mmap(NULL, 4 * page_size, PROT_READ, MAP_SHARED | MAP_FIXED,
+		    data_map_fd, page_size /* initial page shift */);
+	if (CHECK(tmp1 != MAP_FAILED, "adv_mmap7", "unexpected success")) {
+		munmap(tmp1, 4 * page_size);
+		goto cleanup;
+	}
+
 cleanup:
 	if (bss_mmaped)
 		CHECK_FAIL(munmap(bss_mmaped, bss_sz));
-- 
2.25.1


       reply	other threads:[~2020-06-09  0:42 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200608231211.3363633-1-sashal@kernel.org>
2020-06-08 23:02 ` Sasha Levin [this message]
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 068/606] bpf: Fix sk_psock refcnt leak when receiving message Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 075/606] bpf: Enforce returning 0 for fentry/fexit progs Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 076/606] selftests/bpf: Enforce returning 0 for fentry/fexit programs Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 077/606] bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 114/606] net/ena: Fix build warning in ena_xdp_set() Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 141/606] bpf: Restrict bpf_probe_read{, str}() only to archs where they work Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 142/606] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 168/606] kbuild: Remove debug info from kallsyms linking Sasha Levin
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 198/606] flow_dissector: Drop BPF flow dissector prog ref on netns cleanup Sasha Levin
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 202/606] bpf: Prevent mmap()'ing read-only maps as writable Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 243/606] net/tls: fix encryption error checking Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 287/606] samples: bpf: Fix build error Sasha Levin

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