Re: select() call corrupts stack

[Andreas Schwab <schwab@suse.de>]

Artiom Morozov <artiom@phreaker.net> writes:

|> Hello,
|> 
|> 	Here's a sample program. Try running it and open about 2k of
|> 	connections to port 5222 (you'll need ulimit -n 10000 or like
|> 	that). It will segfault. Simple asm like this
|>    __asm__(
|> 	"pushl %eax \n\t" 	"movl  0(%ebp), %eax \n\t"
|> 	"cmp   $65535, %eax \n\t"
|> 	"ja isok \n\t"
|> 	"xor  %eax, %eax \n\t"
|> 	"movl  %eax, 0(%eax) \n\t"	 	"isok: \n\t"
|> 	"popl  %eax \n\t"
|>    );
|> after each subroutine call will show you that after select() [ebp] have
|> weird value. While this is unlikely to be a security flaw, i think this is
|> a bug.
|> 
|> ps: it's okay for 1k of connections or so

/* Number of descriptors that can fit in an `fd_set'.  */
#define __FD_SETSIZE	1024

Use poll(3) instead.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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