The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls, despite being
defined to take a "long" parameter, actually take "int" parameters.
FUSE unfortunately assumed that the ioctl definitions never lie, and
transfers a long's worth of data in and out of userspace, which causes
stack smashing in chattr, and other bugs elsewhere.
So, special-case this in FUSE so that we don't crash userland.
v2: Do the same for the IOC_[GS]ETVERSION ioctls, as Richard Hansen
points out.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/fuse/file.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 7e70506..f8766ab 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2385,6 +2385,22 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
iov->iov_base = (void __user *)arg;
iov->iov_len = _IOC_SIZE(cmd);
+ /*
+ * The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls take int
+ * parameters even though the ioctl definition specifies long.
+ * Userland has been expecting int for ages (and chattr
+ * segfaults on FUSE filesystems), so special case that here.
+ * The IOC32 variants were declared with int, so they don't
+ * need this correction.
+ */
+ switch (cmd) {
+ case FS_IOC_GETFLAGS:
+ case FS_IOC_SETFLAGS:
+ case FS_IOC_GETVERSION:
+ case FS_IOC_SETVERSION:
+ iov->iov_len = sizeof(int);
+ }
+
if (_IOC_DIR(cmd) & _IOC_WRITE) {
in_iov = iov;
in_iovs = 1;
--
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