Hi lianbo
test case is non-elf-vmcore, so all nt_prstatus_percpu invalid pointer.
Thanks
Guanyou.
lijiang <liji...@redhat.com> 于2024年11月26日周二 11:27写道：
> 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>
>> Content-Type: multipart/mixed; boundary="00000000000065fc530625d705b8"
>>
>> --00000000000065fc530625d705b8
>> Content-Type: multipart/alternative;
>> boundary="00000000000065fc530625d705b6"
>>
>> --00000000000065fc530625d705b6
>> Content-Type: text/plain; charset="UTF-8"
>>
>> 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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