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    Subject[PATCH 5.18 145/879] net: remove two BUG() from skb_checksum_help()
    Date
    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit d7ea0d9df2a6265b2b180d17ebc64b38105968fc ]

    I have a syzbot report that managed to get a crash in skb_checksum_help()

    If syzbot can trigger these BUG(), it makes sense to replace
    them with more friendly WARN_ON_ONCE() since skb_checksum_help()
    can instead return an error code.

    Note that syzbot will still crash there, until real bug is fixed.

    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/core/dev.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/net/core/dev.c b/net/core/dev.c
    index 2771fd22dc6a..0784c339cd7d 100644
    --- a/net/core/dev.c
    +++ b/net/core/dev.c
    @@ -3215,11 +3215,15 @@ int skb_checksum_help(struct sk_buff *skb)
    }

    offset = skb_checksum_start_offset(skb);
    - BUG_ON(offset >= skb_headlen(skb));
    + ret = -EINVAL;
    + if (WARN_ON_ONCE(offset >= skb_headlen(skb)))
    + goto out;
    +
    csum = skb_checksum(skb, offset, skb->len - offset, 0);

    offset += skb->csum_offset;
    - BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
    + if (WARN_ON_ONCE(offset + sizeof(__sum16) > skb_headlen(skb)))
    + goto out;

    ret = skb_ensure_writable(skb, offset + sizeof(__sum16));
    if (ret)
    --
    2.35.1


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