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author | Alexey Dobriyan <adobriyan@gmail.com> | 2010-11-22 12:54:21 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2010-11-28 10:39:45 -0800 |
commit | 0147fc058d11bd4009b126d09974d2c8f48fef15 (patch) | |
tree | f73f0e82f7774938dd7190c6a810e0ccb2466f2b /block | |
parent | 8475ef9fd16cadbfc692f78e608d1941a340beb2 (diff) |
tcp: restrict net.ipv4.tcp_adv_win_scale (#20312)
tcp_win_from_space() does the following:
if (sysctl_tcp_adv_win_scale <= 0)
return space >> (-sysctl_tcp_adv_win_scale);
else
return space - (space >> sysctl_tcp_adv_win_scale);
"space" is int.
As per C99 6.5.7 (3) shifting int for 32 or more bits is
undefined behaviour.
Indeed, if sysctl_tcp_adv_win_scale is exactly 32,
space >> 32 equals space and function returns 0.
Which means we busyloop in tcp_fixup_rcvbuf().
Restrict net.ipv4.tcp_adv_win_scale to [-31, 31].
Fix https://bugzilla.kernel.org/show_bug.cgi?id=20312
Steps to reproduce:
echo 32 >/proc/sys/net/ipv4/tcp_adv_win_scale
wget www.kernel.org
[softlockup]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'block')
0 files changed, 0 insertions, 0 deletions