Hi, Guanyou
Thank you for the fix.
On Mon, Nov 4, 2024 at 4:13 PM <devel-requ...@lists.crash-utility.osci.io>
wrote:
> Date: Fri, 1 Nov 2024 18:01:27 +0800
> From: Guanyou Chen <chenguanyou9...@gmail.com>
> Subject: [Crash-utility] [PATCH] bugfix command "help -r" segv fault
> To: Lianbo <liji...@redhat.com>, Tao Liu <l...@redhat.com>,
> devel@lists.crash-utility.osci.io
> Message-ID:
> <CAHS3RMU3nuiqW4z=
> qo9roufadruxcalhyjnxwmcugodb_+3...@mail.gmail.com>
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>
> --00000000000065fc530625d705b8
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>
> Hi Lianbo, Tao
>
> When the ELF Note does not contain CPU registers,
> attempting to retrieve online CPU registers will cause a crash.
>
> After:
> CPU 6:
> help: registers not collected for cpu 6
> ...
>
> Signed-off-by: Guanyou.Chen <chenguan...@xiaomi.com>
> ---
> netdump.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/netdump.c b/netdump.c
> index 8ea5159..435793b 100644
> --- a/netdump.c
> +++ b/netdump.c
> @@ -2780,6 +2780,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
>
I copied the code block here:
display_regs_from_elf_notes(int cpu, FILE *ofp)
{
Elf32_Nhdr *note32;
Elf64_Nhdr *note64;
size_t len;
char *user_regs;
int c, skipped_count;
/*
* Kdump NT_PRSTATUS notes are only related to online cpus,
* so offline cpus should be skipped.
*/
if (pc->flags2 & QEMU_MEM_DUMP_ELF)
skipped_count = 0;
else {
for (c = skipped_count = 0; c < cpu; c++) {
if (check_offline_cpu(c))
skipped_count++;
}
}
if ((cpu - skipped_count) >= nd->num_prstatus_notes &&
!machine_type("MIPS")) {
error(INFO, "registers not collected for cpu %d\n", cpu);
return;
}
...
Could you please point out why the above check does not work?
BTW: I'm not sure if it can work for you, can you help to try this? Just a
guess.
if (((cpu < 0 ) || (!dd->nt_prstatus_percpu[cpu])
|| (cpu - skipped_count) >= nd->num_prstatus_notes) &&
!machine_type("MIPS")) {
error(INFO, "registers not collected for cpu %d\n", cpu);
return;
}
Thanks
Lianbo
nd->nt_prstatus_percpu[cpu];
> else
> note64 = (Elf64_Nhdr *)nd->nt_prstatus;
> + if (!note64) {
> + error(INFO, "registers not collected for cpu %d\n", cpu);
> + return;
> + }
> len = sizeof(Elf64_Nhdr);
> len = roundup(len + note64->n_namesz, 4);
> len = roundup(len + note64->n_descsz, 4);
> @@ -2820,6 +2824,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
> nd->nt_prstatus_percpu[cpu];
> else
> note32 = (Elf32_Nhdr *)nd->nt_prstatus;
> + if (!note32) {
> + error(INFO, "registers not collected for cpu %d\n", cpu);
> + return;
> + }
> len = sizeof(Elf32_Nhdr);
> len = roundup(len + note32->n_namesz, 4);
> len = roundup(len + note32->n_descsz, 4);
> @@ -2857,6 +2865,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
> else
> note64 = (Elf64_Nhdr *)nd->nt_prstatus;
>
> + if (!note64) {
> + error(INFO, "registers not collected for cpu %d\n", cpu);
> + return;
> + }
> prs = (struct ppc64_elf_prstatus *)
> ((char *)note64 + sizeof(Elf64_Nhdr) + note64->n_namesz);
> prs = (struct ppc64_elf_prstatus *)roundup((ulong)prs, 4);
> @@ -2903,6 +2915,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
> nd->nt_prstatus_percpu[cpu];
> else
> note64 = (Elf64_Nhdr *)nd->nt_prstatus;
> + if (!note64) {
> + error(INFO, "registers not collected for cpu %d\n", cpu);
> + return;
> + }
> len = sizeof(Elf64_Nhdr);
> len = roundup(len + note64->n_namesz, 4);
> len = roundup(len + note64->n_descsz, 4);
> --
> 2.34.1
>
> Guanyou.
> Thanks
>
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