[PATCH v3 17/21] vmcore: check NT_VMCORE_PAD as a mark indicating the end of ELF note buffer

[HATAYAMA Daisuke]

Modern kernel marks the end of ELF note buffer with NT_VMCORE_PAD type
note in order to make the buffer satisfy mmap()'s page-size boundary
requirement. This patch makes finishing reading each buffer if the
note type now being read is NT_VMCORE_PAD type.

Signed-off-by: HATAYAMA Daisuke <d.hatay...@jp.fujitsu.com>
---

 fs/proc/vmcore.c |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index b252d17..2a0f885 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -258,12 +258,24 @@ static int __init merge_note_headers_elf64(char *elfptr, 
size_t *elfsz,
                }
                nhdr_ptr = notes_section;
                while (real_sz < max_sz) {
+                       char *name;
+
+                       /* Old kernel marks the end of ELF note buffer
+                        * with empty header. */
                        if (nhdr_ptr->n_namesz == 0)
                                break;
                        sz = sizeof(Elf64_Nhdr) +
                                ((nhdr_ptr->n_namesz + 3) & ~3) +
                                ((nhdr_ptr->n_descsz + 3) & ~3);
                        real_sz += sz;
+
+                       /* Modern kernel marks the end of ELF note
+                        * buffer with NT_VMCORE_PAD type note. */
+                       name = (char *)(nhdr_ptr + 1);
+                       if (strncmp(name, VMCOREINFO_NOTE_NAME,
+                                   sizeof(VMCOREINFO_NOTE_NAME)) == 0
+                           && nhdr_ptr->n_type == NT_VMCORE_PAD)
+                               break;
                        nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
                }
 
@@ -367,12 +379,24 @@ static int __init merge_note_headers_elf32(char *elfptr, 
size_t *elfsz,
                }
                nhdr_ptr = notes_section;
                while (real_sz < max_sz) {
+                       char *name;
+
+                       /* Old kernel marks the end of ELF note buffer
+                        * with empty header. */
                        if (nhdr_ptr->n_namesz == 0)
                                break;
                        sz = sizeof(Elf32_Nhdr) +
                                ((nhdr_ptr->n_namesz + 3) & ~3) +
                                ((nhdr_ptr->n_descsz + 3) & ~3);
                        real_sz += sz;
+
+                       /* Modern kernel marks the end of ELF note
+                        * buffer with NT_VMCORE_PAD type note. */
+                       name = (char *)(nhdr_ptr + 1);
+                       if (strncmp(name, VMCOREINFO_NOTE_NAME,
+                                   sizeof(VMCOREINFO_NOTE_NAME)) == 0
+                           && nhdr_ptr->n_type == NT_VMCORE_PAD)
+                               break;
                        nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
                }
 

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