DivestOS/Patches/Linux_CVEs/CVE-2016-3775/3.4/0001.patch

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From dc18eac80caaa12ff7072df9fe857b921e8c26c7 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 21 May 2012 16:06:20 -0700
Subject: [PATCH] UPSTREAM: vfs: make AIO use the proper rw_verify_area() area
helpers
We had for some reason overlooked the AIO interface, and it didn't use
the proper rw_verify_area() helper function that checks (for example)
mandatory locking on the file, and that the size of the access doesn't
cause us to overflow the provided offset limits etc.
Instead, AIO did just the security_file_permission() thing (that
rw_verify_area() also does) directly.
This fixes it to do all the proper helper functions, which not only
means that now mandatory file locking works with AIO too, we can
actually remove lines of code.
Bug: 28939037
Reported-by: Manish Honap <manish_honap_vit@yahoo.co.in>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit a70b52ec1aaeaf60f4739edb1b422827cb6f3893)
Change-Id: I2e182e973b44ba97c45c80d52d8a0b7c32a72750
---
fs/aio.c | 30 ++++++++++++++----------------
1 file changed, 14 insertions(+), 16 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 67a6db3e1b6f8..e7f2fad7b4ce7 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1456,6 +1456,10 @@ static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
if (ret < 0)
goto out;
+ ret = rw_verify_area(type, kiocb->ki_filp, &kiocb->ki_pos, ret);
+ if (ret < 0)
+ goto out;
+
kiocb->ki_nr_segs = kiocb->ki_nbytes;
kiocb->ki_cur_seg = 0;
/* ki_nbytes/left now reflect bytes instead of segs */
@@ -1467,11 +1471,17 @@ static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
return ret;
}
-static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
+static ssize_t aio_setup_single_vector(int type, struct file * file, struct kiocb *kiocb)
{
+ int bytes;
+
+ bytes = rw_verify_area(type, file, &kiocb->ki_pos, kiocb->ki_left);
+ if (bytes < 0)
+ return bytes;
+
kiocb->ki_iovec = &kiocb->ki_inline_vec;
kiocb->ki_iovec->iov_base = kiocb->ki_buf;
- kiocb->ki_iovec->iov_len = kiocb->ki_left;
+ kiocb->ki_iovec->iov_len = bytes;
kiocb->ki_nr_segs = 1;
kiocb->ki_cur_seg = 0;
return 0;
@@ -1496,10 +1506,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
kiocb->ki_left)))
break;
- ret = security_file_permission(file, MAY_READ);
- if (unlikely(ret))
- break;
- ret = aio_setup_single_vector(kiocb);
+ ret = aio_setup_single_vector(READ, file, kiocb);
if (ret)
break;
ret = -EINVAL;
@@ -1514,10 +1521,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
kiocb->ki_left)))
break;
- ret = security_file_permission(file, MAY_WRITE);
- if (unlikely(ret))
- break;
- ret = aio_setup_single_vector(kiocb);
+ ret = aio_setup_single_vector(WRITE, file, kiocb);
if (ret)
break;
ret = -EINVAL;
@@ -1528,9 +1532,6 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_READ)))
break;
- ret = security_file_permission(file, MAY_READ);
- if (unlikely(ret))
- break;
ret = aio_setup_vectored_rw(READ, kiocb, compat);
if (ret)
break;
@@ -1542,9 +1543,6 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_WRITE)))
break;
- ret = security_file_permission(file, MAY_WRITE);
- if (unlikely(ret))
- break;
ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
if (ret)
break;