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Greetings,
Dirst of all, I'm sorry but I don't know if this has been addressed before, nor if you consider it a bug.
The cenario I'm about to describe will crash the system with a kernel panic; I think that must be considered a bug and should be addressed, although the nature of the changes I'm going to descrive justify easilly what's happening. IMHO there should be an error message, but never a kernel panic and consequent system crash.
This issue was tested on both 2.6.4-mbn1 and 2.6.6, although I'm sure it will happen in every 2.6 and possibly in every 2.4 and 2.2.
As we can read on Documentation/networking/ip-sysctl.txt, /proc/sys/net/ipv4/tcp_rmem is a vercor of 3 integers (min, default and max) which defines the amount of memory reserved/allowed for read buffers for TCP sockets.
If we `echo "0 0 0" > /proc/sys/net/ipv4/rcp_rmem`, we just say that there's no memory for TCP read buffers (or, in other words, the kernel won't be able to read anything TCP).
If we, next, do, for instance, `ssh localhost` (if we have am sshd running, of course), we get a Kernel panic:
divide error: 0000 [#1] [...] Call Trace: [<c03a9b47>] tcp_transmit_skb+0x5a7/0x620 [<c03ac5d5>] tcp_send_ack+0x85/0xd0 [...] Code: f7 fe 89 c1 0f [...] <0>Kernel panic: Fatal exception in interrupt In interrupt habdler - not syncing
I didn't paste here the whole Kernel panic since this is easilly reproduceble.
Mind Booster Noori
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Marcos Daniel Marado Torres AKA Mind Booster Noori
http://student.dei.uc.pt/~marado - marado@student.dei.uc.pt
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