Date: Fri, 20 May 2005 02:29:19 +0200 From: Dirk GOUDERS <gouders@et.bocholt.fh-ge.de> To: freebsd-hackers@freebsd.org Subject: Re: page fault in ugenpoll() Message-ID: <200505200029.j4K0TJNb000312@karga.hank.home> In-Reply-To: Message from Dirk Gouders <gouders@et.bocholt.fh-ge.de> <200505191213.j4JCD7pb000372@karga.hank.home>
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Hello,
just for completeness, I want to provide a simple program that causes
a kernel panic when invoked with the argument /dev/ugen0:
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <poll.h>
#include <errno.h>
int main(int argc, char *argv[])
{
int fd;
int nfd;
char *path = argv[1];
struct pollfd pfd[1];
fd = open(path, O_RDWR);
if ( fd < 0 ) {
fprintf(stderr, "%s: %s\n", path, strerror(errno));
exit(1);
}
pfd[0].fd = fd;
pfd[0].events = POLLHUP;
pfd[0].revents = 0;
nfd = poll(pfd, 1, 10);
if ( nfd < 0 ) {
fprintf(stderr, "poll(2): %s\n", strerror(errno));
exit(1);
}
printf("nfd = %d\n", nfd);
close(fd);
exit(0);
}
> Hello,
>
> on a machine
>
> FreeBSD karga.hank.home 4.11-STABLE FreeBSD 4.11-STABLE #2: Thu May 19 12:32
> :50 CEST 2005 root@karga.hank.home:/usr/src/sys/compile/KARGA i386
>
> I am playing with a Cryptoflex e-gate USB token and get kernel
> panics when invoking a program openct-control to access it:
>
> Fatal trap 12: page fault while in kernel mode
> fault virtual address = 0x3
> fault code = supervisor read, page not present
> instruction pointer = 0x8:0xc027177b
> stack pointer = 0x10:0xccde7d40
> frame pointer = 0x10:0xccde7d50
> code segment = base 0x0, limit 0xfffff, type 0x1b
> = DPL 0, pres 1, def32 1, gran 1
> processor eflags = interrupt enabled, resume, IOPL = 0
> current process = 173 (ifdhandler)
> interrupt mask = bio
> trap number = 12
> panic: page fault
>
> The IP points to the following line in the function ugenpoll (line
> 1445 in ugen.c):
>
> switch (sce->edesc->bmAttributes & UE_XFERTYPE)
>
> Examining sce with gdb gives:
> (kgdb) print sce
> $1 = (struct ugen_endpoint *) 0x68c060
> (kgdb) print sce->edesc
> Cannot access memory at address 0x68c064.
> (kgdb)
>
> The software that I am trying to use might be erroneous, but I am
> wondering that it causes kernel panics by accessing /dev/ugen0.
>
> Dirk
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