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Commit ad8fb61c authored by Magnus Karlsson's avatar Magnus Karlsson Committed by Greg Kroah-Hartman
Browse files

xsk: Add missing check on user supplied headroom size 



[ Upstream commit 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 ]

Add a check that the headroom cannot be larger than the available
space in the chunk. In the current code, a malicious user can set the
headroom to a value larger than the chunk size minus the fixed XDP
headroom. That way packets with a length larger than the supported
size in the umem could get accepted and result in an out-of-bounds
write.

Fixes: c0c77d8f ("xsk: add user memory registration support sockopt")
Reported-by: default avatarBui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: default avatarMagnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=207225
Link: https://lore.kernel.org/bpf/1586849715-23490-1-git-send-email-magnus.karlsson@intel.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 2b486298

net/xdp/xdp_umem.c

+2 −3
Original line number Diff line number Diff line
@@ -260,7 +260,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 
	u32 chunk_size = mr->chunk_size, headroom = mr->headroom;

	unsigned int chunks, chunks_per_page;

	u64 addr = mr->addr, size = mr->len;

	int size_chk, err, i;

	int err, i;



	if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {

		/* Strictly speaking we could support this, if:
@@ -295,8 +295,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 


	headroom = ALIGN(headroom, 64);



	size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;

	if (size_chk < 0)

	if (headroom >= chunk_size - XDP_PACKET_HEADROOM)

		return -EINVAL;



	umem->address = (unsigned long)addr;