Commit d2530b43 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

binfmt_elf: remove the set_fs(KERNEL_DS) in elf_core_dump 



There is no logic in elf_core_dump itself or in the various arch helpers
called from it which use uaccess routines on kernel pointers except for
the file writes thate are nicely encapsulated by using __kernel_write in
dump_emit.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent fa4751f4

fs/binfmt_elf.c

+1 −15
Original line number Diff line number Diff line
@@ -1355,7 +1355,6 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma, 
	    vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ)) {

		u32 __user *header = (u32 __user *) vma->vm_start;

		u32 word;

		mm_segment_t fs = get_fs();

		/*

		 * Doing it this way gets the constant folded by GCC.

		 */
@@ -1368,14 +1367,8 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma, 
		magic.elfmag[EI_MAG1] = ELFMAG1;

		magic.elfmag[EI_MAG2] = ELFMAG2;

		magic.elfmag[EI_MAG3] = ELFMAG3;

		/*

		 * Switch to the user "segment" for get_user(),

		 * then put back what elf_core_dump() had in place.

		 */

		set_fs(USER_DS);

		if (unlikely(get_user(word, header)))

			word = 0;

		set_fs(fs);

		if (word == magic.cmp)

			return PAGE_SIZE;

	}
@@ -2183,7 +2176,6 @@ static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum, 
static int elf_core_dump(struct coredump_params *cprm)

{

	int has_dumped = 0;

	mm_segment_t fs;

	int segs, i;

	size_t vma_data_size = 0;

	struct vm_area_struct *vma, *gate_vma;
@@ -2232,13 +2224,10 @@ static int elf_core_dump(struct coredump_params *cprm) 
	 * notes.  This also sets up the file header.

	 */

	if (!fill_note_info(&elf, e_phnum, &info, cprm->siginfo, cprm->regs))

		goto cleanup;

		goto end_coredump;



	has_dumped = 1;



	fs = get_fs();

	set_fs(KERNEL_DS);



	offset += sizeof(elf);				/* Elf header */

	offset += segs * sizeof(struct elf_phdr);	/* Program headers */
@@ -2366,9 +2355,6 @@ static int elf_core_dump(struct coredump_params *cprm) 
	}



end_coredump:

	set_fs(fs);



cleanup:

	free_note_info(&info);

	kfree(shdr4extnum);

	kvfree(vma_filesz);