diff mbox series

[5.10,CANDIDATE,2/6] xfs: reject crazy array sizes being fed to XFS_IOC_GETBMAP*

Message ID 20220822162802.1661512-3-amir73il@gmail.com (mailing list archive)
State New, archived
Headers show
Series xfs stable candidate patches for 5.10.y (from v5.17) | expand

Commit Message

Amir Goldstein Aug. 22, 2022, 4:27 p.m. UTC 
From: "Darrick J. Wong" <djwong@kernel.org>

commit 29d650f7e3ab55283b89c9f5883d0c256ce478b5 upstream.

Syzbot tripped over the following complaint from the kernel:

WARNING: CPU: 2 PID: 15402 at mm/util.c:597 kvmalloc_node+0x11e/0x125 mm/util.c:597

While trying to run XFS_IOC_GETBMAP against the following structure:

struct getbmap fubar = {
	.bmv_count	= 0x22dae649,
};

Obviously, this is a crazy huge value since the next thing that the
ioctl would do is allocate 37GB of memory.  This is enough to make
kvmalloc mad, but isn't large enough to trip the validation functions.
In other words, I'm fussing with checks that were **already sufficient**
because that's easier than dealing with 644 internal bug reports.  Yes,
that's right, six hundred and forty-four.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Catherine Hoang <catherine.hoang@oracle.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/xfs/xfs_ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index d973350d5946..103fa8381e7d 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1689,7 +1689,7 @@  xfs_ioc_getbmap(
 
 	if (bmx.bmv_count < 2)
 		return -EINVAL;
-	if (bmx.bmv_count > ULONG_MAX / recsize)
+	if (bmx.bmv_count >= INT_MAX / recsize)
 		return -ENOMEM;
 
 	buf = kvzalloc(bmx.bmv_count * sizeof(*buf), GFP_KERNEL);