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| author | Alexei Starovoitov <ast@fb.com> | 2016-03-09 20:02:33 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-03-09 23:27:30 -0500 |
| commit | cdc4e47da8f4c32eeb6b2061a8a834f4362a12b7 (patch) | |
| tree | d66e39c8dccee7e5cf1662305a102c6235d315be /kernel/bpf | |
| parent | b8cdc05173f05d212627b7aba7ec47fa334a79f2 (diff) | |
| download | linux-cdc4e47da8f4c32eeb6b2061a8a834f4362a12b7.tar.gz | |
bpf: avoid copying junk bytes in bpf_get_current_comm()
Lots of places in the kernel use memcpy(buf, comm, TASK_COMM_LEN); but
the result is typically passed to print("%s", buf) and extra bytes
after zero don't cause any harm.
In bpf the result of bpf_get_current_comm() is used as the part of
map key and was causing spurious hash map mismatches.
Use strlcpy() to guarantee zero-terminated string.
bpf verifier checks that output buffer is zero-initialized,
so even for short task names the output buffer don't have junk bytes.
Note it's not a security concern, since kprobe+bpf is root only.
Fixes: ffeedafbf023 ("bpf: introduce current->pid, tgid, uid, gid, comm accessors")
Reported-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/helpers.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 4504ca66118d..50da680c479f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -166,7 +166,7 @@ static u64 bpf_get_current_comm(u64 r1, u64 size, u64 r3, u64 r4, u64 r5) if (!task) return -EINVAL; - memcpy(buf, task->comm, min_t(size_t, size, sizeof(task->comm))); + strlcpy(buf, task->comm, min_t(size_t, size, sizeof(task->comm))); return 0; } |