From 481fe17e973fb97aa3edf17c69557afe88d8334f Mon Sep 17 00:00:00 2001
From: Haogang Chen <haogangchen@gmail.com>
Date: Mon, 19 Dec 2011 17:11:56 -0800
Subject: [PATCH] nilfs2: potential integer overflow in
nilfs_ioctl_clean_segments()
There is a potential integer overflow in nilfs_ioctl_clean_segments().
When a large argv[n].v_nmembs is passed from the userspace, the subsequent
call to vmalloc() will allocate a buffer smaller than expected, which
leads to out-of-bound access in nilfs_ioctl_move_blocks() and
lfs_clean_segments().
The following check does not prevent the overflow because nsegs is also
controlled by the userspace and could be very large.
if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
goto out_free;
This patch clamps argv[n].v_nmembs to UINT_MAX / argv[n].v_size, and
returns -EINVAL when overflow.
Signed-off-by: Haogang Chen <haogangchen@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/nilfs2/ioctl.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 3e654273cfc2..ac258beeda3c 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -625,6 +625,9 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
goto out_free;
+ if (argv[n].v_nmembs >= UINT_MAX / argv[n].v_size)
+ goto out_free;
+
len = argv[n].v_size * argv[n].v_nmembs;
base = (void __user *)(unsigned long)argv[n].v_base;
if (len == 0) {
--
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