| Date | Mon, 25 Apr 2011 22:05:13 +0200 | From | Willy Tarreau <> | Subject | [PATCH 161/173] xfs: zero proper structure size for geometry calls |
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2.6.27.59-stable review patch. If anyone has any objections, please let us know.
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From: Alex Elder <aelder@sgi.com>
commit af24ee9ea8d532e16883251a6684dfa1be8eec29 upstream.
Commit 493f3358cb289ccf716c5a14fa5bb52ab75943e5 added this call to xfs_fs_geometry() in order to avoid passing kernel stack data back to user space:
+ memset(geo, 0, sizeof(*geo));
Unfortunately, one of the callers of that function passes the address of a smaller data type, cast to fit the type that xfs_fs_geometry() requires. As a result, this can happen:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: f87aca93
Pid: 262, comm: xfs_fsr Not tainted 2.6.38-rc6-493f3358cb2+ #1 Call Trace:
[<c12991ac>] ? panic+0x50/0x150 [<c102ed71>] ? __stack_chk_fail+0x10/0x18 [<f87aca93>] ? xfs_ioc_fsgeometry_v1+0x56/0x5d [xfs]
Fix this by fixing that one caller to pass the right type and then copy out the subset it is interested in.
Note: This patch is an alternative to one originally proposed by Eric Sandeen.
Reported-by: Jeffrey Hundstad <jeffrey.hundstad@mnsu.edu> Signed-off-by: Alex Elder <aelder@sgi.com> Reviewed-by: Eric Sandeen <sandeen@redhat.com> Tested-by: Jeffrey Hundstad <jeffrey.hundstad@mnsu.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/xfs/linux-2.6/xfs_ioctl.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/fs/xfs/linux-2.6/xfs_ioctl.c +++ b/fs/xfs/linux-2.6/xfs_ioctl.c @@ -697,14 +697,19 @@ xfs_ioc_fsgeometry_v1( xfs_mount_t *mp, void __user *arg) { - xfs_fsop_geom_v1_t fsgeo; + xfs_fsop_geom_t fsgeo; int error; - error = xfs_fs_geometry(mp, (xfs_fsop_geom_t *)&fsgeo, 3); + error = xfs_fs_geometry(mp, &fsgeo, 3); if (error) return -error; - if (copy_to_user(arg, &fsgeo, sizeof(fsgeo))) + /* + * Caller should have passed an argument of type + * xfs_fsop_geom_v1_t. This is a proper subset of the + * xfs_fsop_geom_t that xfs_fs_geometry() fills in. + */ + if (copy_to_user(arg, &fsgeo, sizeof(xfs_fsop_geom_v1_t))) return -XFS_ERROR(EFAULT); return 0; }
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