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

[Zhang Yanfei]

ä 2013å03æ02æ 16:35, HATAYAMA Daisuke åé:
> 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@xxxxxxxxxxxxxx>

> 
> Signed-off-by: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
> ---
> 
>  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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> 

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