Commit afc63a97 authored by Jann Horn's avatar Jann Horn Committed by Linus Torvalds
Browse files

coredump: refactor page range dumping into common helper 



Both fs/binfmt_elf.c and fs/binfmt_elf_fdpic.c need to dump ranges of
pages into the coredump file.  Extract that logic into a common helper.

Signed-off-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-4-jannh@google.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent df0c09c0

fs/binfmt_elf.c

+2 −20
Original line number Diff line number Diff line
@@ -2444,27 +2444,9 @@ static int elf_core_dump(struct coredump_params *cprm) 


	for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;

			vma = next_vma(vma, gate_vma)) {

		unsigned long addr;

		unsigned long end;



		end = vma->vm_start + vma_filesz[i++];



		for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {

			struct page *page;

			int stop;



			page = get_dump_page(addr);

			if (page) {

				void *kaddr = kmap(page);

				stop = !dump_emit(cprm, kaddr, PAGE_SIZE);

				kunmap(page);

				put_page(page);

			} else

				stop = !dump_skip(cprm, PAGE_SIZE);

			if (stop)

		if (!dump_user_range(cprm, vma->vm_start, vma_filesz[i++]))

			goto end_coredump;

	}

	}

	dump_truncate(cprm);



	if (!elf_core_write_extra_data(cprm))

fs/binfmt_elf_fdpic.c

+3 −15
Original line number Diff line number Diff line
@@ -1534,22 +1534,10 @@ static bool elf_fdpic_dump_segments(struct coredump_params *cprm) 
		if (!maydump(vma, cprm->mm_flags))

			continue;



		for (addr = vma->vm_start; addr < vma->vm_end;

							addr += PAGE_SIZE) {

			bool res;

			struct page *page = get_dump_page(addr);

			if (page) {

				void *kaddr = kmap(page);

				res = dump_emit(cprm, kaddr, PAGE_SIZE);

				kunmap(page);

				put_page(page);

			} else {

				res = dump_skip(cprm, PAGE_SIZE);

			}

			if (!res)

		if (!dump_user_range(cprm, vma->vm_start,

				     vma->vma_end - vma->vm_start))

			return false;

	}

	}

	return true;

}

fs/coredump.c

+34 −0
Original line number Diff line number Diff line
@@ -876,6 +876,40 @@ int dump_skip(struct coredump_params *cprm, size_t nr) 
}

EXPORT_SYMBOL(dump_skip);



#ifdef CONFIG_ELF_CORE

int dump_user_range(struct coredump_params *cprm, unsigned long start,

		    unsigned long len)

{

	unsigned long addr;



	for (addr = start; addr < start + len; addr += PAGE_SIZE) {

		struct page *page;

		int stop;



		/*

		 * To avoid having to allocate page tables for virtual address

		 * ranges that have never been used yet, and also to make it

		 * easy to generate sparse core files, use a helper that returns

		 * NULL when encountering an empty page table entry that would

		 * otherwise have been filled with the zero page.

		 */

		page = get_dump_page(addr);

		if (page) {

			void *kaddr = kmap(page);



			stop = !dump_emit(cprm, kaddr, PAGE_SIZE);

			kunmap(page);

			put_page(page);

		} else {

			stop = !dump_skip(cprm, PAGE_SIZE);

		}

		if (stop)

			return 0;

	}

	return 1;

}

#endif



int dump_align(struct coredump_params *cprm, int align)

{

	unsigned mod = cprm->pos & (align - 1);

include/linux/coredump.h

+2 −0
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ extern int dump_skip(struct coredump_params *cprm, size_t nr); 
extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);

extern int dump_align(struct coredump_params *cprm, int align);

extern void dump_truncate(struct coredump_params *cprm);

int dump_user_range(struct coredump_params *cprm, unsigned long start,

		    unsigned long len);

#ifdef CONFIG_COREDUMP

extern void do_coredump(const kernel_siginfo_t *siginfo);

#else