[PATCH] Fix handling of ELF segments with zero filesize (dda6ebde) · Commits · 戴 / test

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:

David Gibson <david@gibson.dropbear.id.au> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

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);
		}

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