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Commit b406472b authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
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net: ipv4: avoid mixed n_redirects and rate_tokens usage



Since commit c09551c6 ("net: ipv4: use a dedicated counter
for icmp_v4 redirect packets") we use 'n_redirects' to account
for redirect packets, but we still use 'rate_tokens' to compute
the redirect packets exponential backoff.

If the device sent to the relevant peer any ICMP error packet
after sending a redirect, it will also update 'rate_token' according
to the leaking bucket schema; typically 'rate_token' will raise
above BITS_PER_LONG and the redirect packets backoff algorithm
will produce undefined behavior.

Fix the issue using 'n_redirects' to compute the exponential backoff
in ip_rt_send_redirect().

Note that we still clear rate_tokens after a redirect silence period,
to avoid changing an established behaviour.

The root cause predates git history; before the mentioned commit in
the critical scenario, the kernel stopped sending redirects, after
the mentioned commit the behavior more randomic.

Reported-by: default avatarXiumei Mu <xmu@redhat.com>
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Fixes: c09551c6 ("net: ipv4: use a dedicated counter for icmp_v4 redirect packets")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarLorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a54cdeeb
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