Date: Tue, 3 Sep 2002 02:18:24 -0700 (PDT) From: Don Lewis <dl-freebsd@catspoiler.org> To: kris@obsecurity.org Cc: current@FreeBSD.ORG Subject: Re: Page faults from bento cluster (Re: Problems reading vmcores) Message-ID: <200209030918.g839IOwr073668@gw.catspoiler.org> In-Reply-To: <20020901035735.GA9690@xor.obsecurity.org>
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On 31 Aug, Kris Kennaway wrote:
> Another one. I have the cores if anyone needs to look at
> them..otherwise I'll stop posting these for now.
>
> Kris
>
> panic: page fault
> panic messages:
> ---
> Fatal trap 12: page fault while in kernel mode
> fault virtual address = 0x4
> fault code = supervisor read, page not present
> #6 0xc0399a48 in calltrap () at {standard input}:98
> #7 0xc021d91f in exec_elf32_imgact (imgp=0xda326bb4) at imgact_elf.c:607
> #8 0xc022a9a2 in execve (td=0xc484c240, uap=0xda326d10)
> at /usr/src/sys/kern/kern_exec.c:280
> #9 0xc03a8a31 in syscall (frame=
> {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = 135022716, tf_esi = 0, tf_ebp = -1077940704, tf_isp = -634229388, tf_ebx = 135022736, tf_edx = 135022736, tf_ecx = 135022895, tf_eax = 59, tf_trapno = 12, tf_err = 2, tf_eip = 134697908, tf_cs = 31, tf_eflags = 659, tf_esp = -1077940748, tf_ss = 47})
> at /usr/src/sys/i386/i386/trap.c:1050
> #10 0xc0399a9d in Xint0x80_syscall () at {standard input}:140
> ---Can't read userspace from dump, or kernel process---
Line 607 is the inner if statement in the loop below:
/* If the executable has a brand, search for it in the brand list. */
if (brand_info == NULL) {
for (i = 0; i < MAX_BRANDS; i++) {
Elf_Brandinfo *bi = elf_brand_list[i];
if (bi != NULL &&
(hdr->e_ident[EI_OSABI] == bi->brand
|| 0 ==
strncmp((const char *)&hdr->e_ident[OLD_EI_BRAND],
bi->compat_3_brand, strlen(bi->compat_3_brand)))) {
brand_info = bi;
break;
}
}
}
Structure member compat_3_brand is at offset 4, but I don't see how we
could be getting that far because of the 'bi != NULL' check.
Can you point gdb at the core file and print the values of bi and hdr?
BTW, this code has changed a lot since your kernel was generated.
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