VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Kees Cook <keescook@chromium.org> 2016-08-02 14:04:51 -0700 committer: Linus Torvalds <torvalds@linux-foundation.org> 2016-08-02 19:35:14 -0400 commit: 0036d1f7eb95bcc52977f15507f00dd07018e7e2 parent: 45107ff6d5265b9786c62b694140d839bc3d2433
Commit Summary:
binfmt_elf: fix calculations for bss padding
Diffstat:
1 file changed, 18 insertions, 14 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a7a28110dc80..7f6aff3f72eb 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -605,28 +605,30 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 			 * Do the same thing for the memory mapping - between
 			 * elf_bss and last_bss is the bss section.
 			 */
-			k = load_addr + eppnt->p_memsz + eppnt->p_vaddr;
+			k = load_addr + eppnt->p_vaddr + eppnt->p_memsz;
 			if (k > last_bss)
 				last_bss = k;
 		}
 	}
 
+	/*
+	 * Now fill out the bss section: first pad the last page from
+	 * the file up to the page boundary, and zero it from elf_bss
+	 * up to the end of the page.
+	 */
+	if (padzero(elf_bss)) {
+		error = -EFAULT;
+		goto out;
+	}
+	/*
+	 * Next, align both the file and mem bss up to the page size,
+	 * since this is where elf_bss was just zeroed up to, and where
+	 * last_bss will end after the vm_brk() below.
+	 */
+	elf_bss = ELF_PAGEALIGN(elf_bss);
+	last_bss = ELF_PAGEALIGN(last_bss);
+	/* Finally, if there is still more bss to allocate, do it. */
 	if (last_bss > elf_bss) {
-		/*
-		 * Now fill out the bss section.  First pad the last page up
-		 * to the page boundary, and then perform a mmap to make sure
-		 * that there are zero-mapped pages up to and including the
-		 * last bss page.
-		 */
-		if (padzero(elf_bss)) {
-			error = -EFAULT;
-			goto out;
-		}
-
-		/* What we have mapped so far */
-		elf_bss = ELF_PAGESTART(elf_bss + ELF_MIN_ALIGN - 1);
-
-		/* Map the last of the bss segment */
 		error = vm_brk(elf_bss, last_bss - elf_bss);
 		if (error)
 			goto out;