162 lines
5.1 KiB
Diff
162 lines
5.1 KiB
Diff
From db8c030857b4e318728c51c20da687906c109d0d Mon Sep 17 00:00:00 2001
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From: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
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Date: Tue, 30 May 2023 19:38:34 +0900
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Subject: [PATCH] diskdump/netdump: fix segmentation fault caused by failure of
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stopping CPUs
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There's no NMI on ARM. Hence, stopping the non-panicking CPUs from the
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panicking CPU via IPI can fail easily if interrupts are being masked
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in those moment. Moreover, crash_notes are not initialized for such
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unstopped CPUs and the corresponding NT_PRSTATUS notes are not
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attached to vmcore. However, crash utility never takes it
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consideration such uninitialized crash_notes and then ends with
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mapping different NT_PRSTATUS to actually unstopped CPUs. This corrupt
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mapping can result crash utility into segmentation fault in the
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operations where register values in NT_PRSTATUS notes are used.
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For example:
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crash> bt 1408
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PID: 1408 TASK: ffff000003e22200 CPU: 2 COMMAND: "repro"
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Segmentation fault (core dumped)
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crash> help -D
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diskdump_data:
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filename: 127.0.0.1-2023-05-26-02:21:27/vmcore-ld1
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flags: 46 (KDUMP_CMPRS_LOCAL|ERROR_EXCLUDED|LZO_SUPPORTED)
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...snip...
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notes_buf: 1815df0
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num_vmcoredd_notes: 0
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num_prstatus_notes: 5
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notes[0]: 1815df0 (NT_PRSTATUS)
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si.signo: 0 si.code: 0 si.errno: 0
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...snip...
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PSTATE: 80400005 FPVALID: 00000000
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notes[4]: 1808f10 (NT_PRSTATUS)
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Segmentation fault (core dumped)
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To fix this issue, let's map NT_PRSTATUS to some CPU only if the
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corresponding crash_notes is checked to be initialized.
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[ kh: moved existence check for crash_notes out of the loop ]
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Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
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Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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---
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defs.h | 1 +
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diskdump.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
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netdump.c | 7 ++++++-
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3 files changed, 51 insertions(+), 2 deletions(-)
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diff --git a/defs.h b/defs.h
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index 7d8bb8ab..6520d2f1 100644
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--- a/defs.h
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+++ b/defs.h
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@@ -7118,6 +7118,7 @@ int dumpfile_is_split(void);
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void show_split_dumpfiles(void);
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void x86_process_elf_notes(void *, unsigned long);
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void *diskdump_get_prstatus_percpu(int);
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+int have_crash_notes(int cpu);
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void map_cpus_to_prstatus_kdump_cmprs(void);
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void diskdump_display_regs(int, FILE *);
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void process_elf32_notes(void *, ulong);
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diff --git a/diskdump.c b/diskdump.c
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index 94bca4de..2c284ff3 100644
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--- a/diskdump.c
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+++ b/diskdump.c
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@@ -101,12 +101,54 @@ int dumpfile_is_split(void)
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return KDUMP_SPLIT();
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}
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+int have_crash_notes(int cpu)
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+{
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+ ulong crash_notes, notes_ptr;
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+ char *buf, *p;
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+ Elf64_Nhdr *note = NULL;
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+
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+ if (!readmem(symbol_value("crash_notes"), KVADDR, &crash_notes,
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+ sizeof(crash_notes), "crash_notes", RETURN_ON_ERROR)) {
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+ error(WARNING, "cannot read \"crash_notes\"\n");
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+ return FALSE;
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+ }
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+
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+ if ((kt->flags & SMP) && (kt->flags & PER_CPU_OFF))
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+ notes_ptr = crash_notes + kt->__per_cpu_offset[cpu];
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+ else
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+ notes_ptr = crash_notes;
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+
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+ buf = GETBUF(SIZE(note_buf));
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+
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+ if (!readmem(notes_ptr, KVADDR, buf,
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+ SIZE(note_buf), "note_buf_t", RETURN_ON_ERROR)) {
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+ error(WARNING, "cpu %d: cannot read NT_PRSTATUS note\n", cpu);
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+ return FALSE;
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+ }
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+
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+ note = (Elf64_Nhdr *)buf;
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+ p = buf + sizeof(Elf64_Nhdr);
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+
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+ if (note->n_type != NT_PRSTATUS) {
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+ error(WARNING, "cpu %d: invalid NT_PRSTATUS note (n_type != NT_PRSTATUS)\n", cpu);
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+ return FALSE;
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+ }
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+
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+ if (!STRNEQ(p, "CORE")) {
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+ error(WARNING, "cpu %d: invalid NT_PRSTATUS note (name != \"CORE\")\n", cpu);
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+ return FALSE;
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+ }
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+
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+ return TRUE;
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+}
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+
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void
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map_cpus_to_prstatus_kdump_cmprs(void)
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{
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void **nt_ptr;
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int online, i, j, nrcpus;
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size_t size;
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+ int crash_notes_exists;
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if (pc->flags2 & QEMU_MEM_DUMP_COMPRESSED) /* notes exist for all cpus */
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goto resize_note_pointers;
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@@ -129,9 +171,10 @@ map_cpus_to_prstatus_kdump_cmprs(void)
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* Re-populate the array with the notes mapping to online cpus
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*/
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nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
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+ crash_notes_exists = kernel_symbol_exists("crash_notes");
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for (i = 0, j = 0; i < nrcpus; i++) {
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- if (in_cpu_map(ONLINE_MAP, i)) {
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+ if (in_cpu_map(ONLINE_MAP, i) && (!crash_notes_exists || have_crash_notes(i))) {
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dd->nt_prstatus_percpu[i] = nt_ptr[j++];
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dd->num_prstatus_notes =
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MAX(dd->num_prstatus_notes, i+1);
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diff --git a/netdump.c b/netdump.c
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index 4eba66ce..61ddeaa0 100644
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--- a/netdump.c
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+++ b/netdump.c
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@@ -75,6 +75,7 @@ map_cpus_to_prstatus(void)
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void **nt_ptr;
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int online, i, j, nrcpus;
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size_t size;
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+ int crash_notes_exists;
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if (pc->flags2 & QEMU_MEM_DUMP_ELF) /* notes exist for all cpus */
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return;
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@@ -97,10 +98,14 @@ map_cpus_to_prstatus(void)
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* Re-populate the array with the notes mapping to online cpus
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*/
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nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
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+ crash_notes_exists = kernel_symbol_exists("crash_notes");
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for (i = 0, j = 0; i < nrcpus; i++) {
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- if (in_cpu_map(ONLINE_MAP, i))
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+ if (in_cpu_map(ONLINE_MAP, i) && (!crash_notes_exists || have_crash_notes(i))) {
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nd->nt_prstatus_percpu[i] = nt_ptr[j++];
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+ nd->num_prstatus_notes =
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+ MAX(nd->num_prstatus_notes, i+1);
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+ }
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}
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FREEBUF(nt_ptr);
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