[PATCH] FDPIC: Check that the size returned by kernel_read() is what we asked for

[David Howells <dhowells@redhat.com>]

From: David Howells <dhowells@redhat.com>

Check that the size of the read returned by kernel_read() is what we asked for.
If it isn't, then reject the binary as being a badly formatted.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/binfmt_elf_fdpic.c |   14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)


diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 32649f2..ddd35d8 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -136,8 +136,8 @@ static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
 
 	retval = kernel_read(file, params->hdr.e_phoff,
 			     (char *) params->phdrs, size);
-	if (retval < 0)
-		return retval;
+	if (unlikely(retval != size))
+		return retval < 0 ? retval : -ENOEXEC;
 
 	/* determine stack size for this binary */
 	phdr = params->phdrs;
@@ -218,8 +218,11 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
 					     phdr->p_offset,
 					     interpreter_name,
 					     phdr->p_filesz);
-			if (retval < 0)
+			if (unlikely(retval != phdr->p_filesz)) {
+				if (retval >= 0)
+					retval = -ENOEXEC;
 				goto error;
+			}
 
 			retval = -ENOENT;
 			if (interpreter_name[phdr->p_filesz - 1] != '\0')
@@ -245,8 +248,11 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
 
 			retval = kernel_read(interpreter, 0, bprm->buf,
 					     BINPRM_BUF_SIZE);
-			if (retval < 0)
+			if (unlikely(retval != BINPRM_BUF_SIZE)) {
+				if (retval >= 0)
+					retval = -ENOEXEC;
 				goto error;
+			}
 
 			interp_params.hdr = *((struct elfhdr *) bprm->buf);
 			break;