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Commit 4faf940d authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: simplify __is_valid_access test on cb 



The __is_valid_access() test for cb[] from 62c7989b ("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 2d071c64
("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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 18702414

net/core/filter.c

+2 −13
Original line number Diff line number Diff line
@@ -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: