Re: [PATCH v2 01/20] vmcore: refer to e_phoff member explicitly

Zhang Yanfei
2013-03-05T07:37:49Z

于 2013年03月02日 16:35, HATAYAMA Daisuke 写道:
> Code around /proc/vmcore currently assumes 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, now refer to
> e_phoff member that indicates position of program header table in
> file-offset.

Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

>
> Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
> ---
>
> fs/proc/vmcore.c | 40 ++++++++++++++++++++--------------------
> 1 files changed, 20 insertions(+), 20 deletions(-)
>
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index b870f74..abf4f01 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) {
> @@ -553,7 +553,7 @@ static int __init parse_crash_elf64_headers(void)
> }
>
> /* Read in all elf headers. */
> - elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
> + elfcorebuf_sz = ehdr.e_phoff + ehdr.e_phnum * sizeof(Elf64_Phdr);
> elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
> if (!elfcorebuf)
> return -ENOMEM;
> @@ -608,7 +608,7 @@ static int __init parse_crash_elf32_headers(void)
> }
>
> /* Read in all elf headers. */
> - elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
> + elfcorebuf_sz = ehdr.e_phoff + ehdr.e_phnum * sizeof(Elf32_Phdr);
> elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
> if (!elfcorebuf)
> return -ENOMEM;
>
>
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