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bpf: simplify __is_valid_access test on cb 

The __is_valid_access() test for cb[] from 62c7989b24 ("bpf: allow
b/h/w/dw access for bpf's cb in ctx") was done unnecessarily complex,
we can just simplify it the same way as recent fix from 2d071c643f
("bpf, trace: make ctx access checks more robust") did. Overflow can
never happen as size is 1/2/4/8 depending on access.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2017-01-24 01:06:26 +01:00 committed by David S. Miller
parent 187024144c
commit 4faf940dd8
1 changed files with 2 additions and 13 deletions
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15
net/core/filter.c
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@ -2784,19 +2784,8 @@ static bool __is_valid_access(int off, int size)
switch (off) {
case offsetof(struct __sk_buff, cb[0]) ...
offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1:
if (size == sizeof(__u16) &&
off > offsetof(struct __sk_buff, cb[4]) + sizeof(__u16))
return false;
if (size == sizeof(__u32) &&
off > offsetof(struct __sk_buff, cb[4]))
return false;
if (size == sizeof(__u64) &&
off > offsetof(struct __sk_buff, cb[2]))
return false;
if (size != sizeof(__u8) &&
size != sizeof(__u16) &&
size != sizeof(__u32) &&
size != sizeof(__u64))
if (off + size >
offsetof(struct __sk_buff, cb[4]) + sizeof(__u32))
return false;
break;
default: