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Commit dda6ebde authored by David Gibson's avatar David Gibson Committed by Linus Torvalds
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[PATCH] Fix handling of ELF segments with zero filesize 



mmap() returns -EINVAL if given a zero length, and thus elf_map() in
binfmt_elf.c does likewise if it attempts to map a (page-aligned) ELF
segment with zero filesize.  Such a situation never arises with the default
linker scripts, but there's nothing inherently wrong with zero-filesize
(but non-zero memsize) ELF segments.  Custom linker scripts can generate
them, and the kernel should be able to map them; this patch makes it so.

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent cc398c2e

fs/binfmt_elf.c

+9 −3
Original line number Diff line number Diff line
@@ -288,11 +288,17 @@ static unsigned long elf_map(struct file *filep, unsigned long addr, 
			struct elf_phdr *eppnt, int prot, int type)

{

	unsigned long map_addr;

	unsigned long pageoffset = ELF_PAGEOFFSET(eppnt->p_vaddr);



	down_write(&current->mm->mmap_sem);

	/* mmap() will return -EINVAL if given a zero size, but a

	 * segment with zero filesize is perfectly valid */

	if (eppnt->p_filesz + pageoffset)

		map_addr = do_mmap(filep, ELF_PAGESTART(addr),

			   eppnt->p_filesz + ELF_PAGEOFFSET(eppnt->p_vaddr), prot, type,

			   eppnt->p_offset - ELF_PAGEOFFSET(eppnt->p_vaddr));

				   eppnt->p_filesz + pageoffset, prot, type,

				   eppnt->p_offset - pageoffset);

	else

		map_addr = ELF_PAGESTART(addr);

	up_write(&current->mm->mmap_sem);

	return(map_addr);

}