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@xxxxxxxxx>
---
fs/nilfs2/ioctl.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 41d6743..b805df9 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) {
--
1.7.5.4
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