[PATCH v3 01/21] vmcore: reference e_phoff member explicitly to get position of program header table

HATAYAMA Daisuke
2013-03-19T02:30:13Z

Currently, the code assumes that position of program header table is
next to ELF header. But future change can break the assumption on
kexec-tools and the 1st kernel. To avoid worst case, reference e_phoff
member explicitly to get position of program header table in
file-offset.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
---

fs/proc/vmcore.c | 56 +++++++++++++++++++++++++++++++++++-------------------
1 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index b870f74..163281e 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -221,8 +221,8 @@ static u64 __init get_vmcore_size_elf64(char *elfptr)
Elf64_Phdr *phdr_ptr;

ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
- size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff);
+ size = ehdr_ptr->e_phoff + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
for (i = 0; i < ehdr_ptr->e_phnum; i++) {
size += phdr_ptr->p_memsz;
phdr_ptr++;
@@ -238,8 +238,8 @@ static u64 __init get_vmcore_size_elf32(char *elfptr)
Elf32_Phdr *phdr_ptr;

ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
- size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff);
+ size = ehdr_ptr->e_phoff + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
for (i = 0; i < ehdr_ptr->e_phnum; i++) {
size += phdr_ptr->p_memsz;
phdr_ptr++;
@@ -259,7 +259,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
u64 phdr_sz = 0, note_off;

ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
int j;
void *notes_section;
@@ -305,7 +305,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
- note_off = sizeof(Elf64_Ehdr) +
+ note_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
phdr.p_offset = note_off;
phdr.p_vaddr = phdr.p_paddr = 0;
@@ -313,14 +313,14 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
phdr.p_align = 0;

/* Add merged PT_NOTE program header*/
- tmp = elfptr + sizeof(Elf64_Ehdr);
+ tmp = elfptr + ehdr_ptr->e_phoff;
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);

/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
*elfsz = *elfsz - i;
- memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
+ memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf64_Phdr)));

/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
@@ -340,7 +340,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
u64 phdr_sz = 0, note_off;

ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
int j;
void *notes_section;
@@ -386,7 +386,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
- note_off = sizeof(Elf32_Ehdr) +
+ note_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
phdr.p_offset = note_off;
phdr.p_vaddr = phdr.p_paddr = 0;
@@ -394,14 +394,14 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
phdr.p_align = 0;

/* Add merged PT_NOTE program header*/
- tmp = elfptr + sizeof(Elf32_Ehdr);
+ tmp = elfptr + ehdr_ptr->e_phoff;
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);

/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
*elfsz = *elfsz - i;
- memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
+ memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf32_Phdr)));

/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
@@ -422,10 +422,10 @@ static int __init process_ptload_program_headers_elf64(char *elfptr,
struct vmcore *new;

ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff); /* PT_NOTE hdr */

/* First program header is PT_NOTE header. */
- vmcore_off = sizeof(Elf64_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
phdr_ptr->p_memsz; /* Note sections */

@@ -459,10 +459,10 @@ static int __init process_ptload_program_headers_elf32(char *elfptr,
struct vmcore *new;

ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff); /* PT_NOTE hdr */

/* First program header is PT_NOTE header. */
- vmcore_off = sizeof(Elf32_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
phdr_ptr->p_memsz; /* Note sections */

@@ -496,7 +496,7 @@ static void __init set_vmcore_list_offsets_elf64(char *elfptr,
ehdr_ptr = (Elf64_Ehdr *)elfptr;

/* Skip Elf header and program headers. */
- vmcore_off = sizeof(Elf64_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);

list_for_each_entry(m, vc_list, list) {
@@ -516,7 +516,7 @@ static void __init set_vmcore_list_offsets_elf32(char *elfptr,
ehdr_ptr = (Elf32_Ehdr *)elfptr;

/* Skip Elf header and program headers. */
- vmcore_off = sizeof(Elf32_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);

list_for_each_entry(m, vc_list, list) {
@@ -558,11 +558,19 @@ static int __init parse_crash_elf64_headers(void)
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
- rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
+ rc = read_from_oldmem(elfcorebuf, sizeof(Elf64_Ehdr), &addr, 0);
if (rc < 0) {
kfree(elfcorebuf);
return rc;
}
+ addr = elfcorehdr_addr + ehdr.e_phoff;
+ rc = read_from_oldmem(elfcorebuf + sizeof(Elf64_Ehdr),
+ ehdr.e_phnum * sizeof(Elf64_Phdr), &addr, 0);
+ if (rc < 0) {
+ kfree(elfcorebuf);
+ return rc;
+ }
+ ((Elf64_Ehdr *)elfcorebuf)->e_phoff = sizeof(Elf64_Ehdr);

/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
@@ -613,11 +621,19 @@ static int __init parse_crash_elf32_headers(void)
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
- rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
+ rc = read_from_oldmem(elfcorebuf, sizeof(Elf32_Ehdr), &addr, 0);
+ if (rc < 0) {
+ kfree(elfcorebuf);
+ return rc;
+ }
+ addr = elfcorehdr_addr + ehdr.e_phoff;
+ rc = read_from_oldmem(elfcorebuf + sizeof(Elf32_Ehdr),
+ ehdr.e_phnum * sizeof(Elf32_Phdr), &addr, 0);
if (rc < 0) {
kfree(elfcorebuf);
return rc;
}
+ ((Elf32_Ehdr *)elfcorebuf)->e_phoff = sizeof(Elf32_Ehdr);

/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);