From: Tore Anderson <tore@linpro.no>
To: linux-kernel@vger.kernel.org
Subject: [BUG] scheduling while atomic when lseek()ing in /proc/net/tcp
Date: Fri, 28 Nov 2003 00:05:35 +0100 [thread overview]
Message-ID: <1069974335.14367.17.camel@echo.linpro.no> (raw)
Hi,
The following code instantly freezes my all of my machines running
any of the beavers:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
int main(void) {
char buf[8192];
int fd, chars;
fd = open("/proc/net/tcp", O_RDONLY);
chars = read(fd, buf, sizeof(buf));
lseek(fd, -chars+1, SEEK_CUR);
close(fd);
return 0;
}
It only happens when I lseek() anywhere from -chars+1 to -chars+150
inclusive (in other words, somewhere on the first line). I do not
need root to abuse this, which makes it an excellent DoS attack for
anyone with an unprivileged account.
I do get an oops, but as I do not have a serial console I'd rather
not transcribe it to paper and post it unless it's crucial to
pinpointing the bug.
--
Tore Anderson
next reply other threads:[~2003-11-27 23:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-27 23:05 Tore Anderson [this message]
2003-11-28 6:19 ` [BUG] scheduling while atomic when lseek()ing in /proc/net/tcp Raj
2003-11-28 17:12 ` OGAWA Hirofumi
2003-11-30 4:42 ` David S. Miller
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