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

HATAYAMA Daisuke
2013-03-19T02:31:41Z

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.hatayama@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);
}