From 3066ff93476c35679cb07a97cce37d9bb07632ff Mon Sep 17 00:00:00 2001
From: Bernd Schubert <bschubert@ddn.com>
Date: Fri, 15 Apr 2022 13:53:56 +0200
Subject: [PATCH] fuse: Apply flags2 only when userspace set the FUSE_INIT_EXT
This is just a safety precaution to avoid checking flags on memory that was
initialized on the user space side. libfuse zeroes struct fuse_init_out
outarg, but this is not guranteed to be done in all implementations.
Better is to act on flags and to only apply flags2 when FUSE_INIT_EXT is
set.
There is a risk with this change, though - it might break existing user
space libraries, which are already using flags2 without setting
FUSE_INIT_EXT.
The corresponding libfuse patch is here
https://github.com/libfuse/libfuse/pull/662
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Fixes: 53db28933e95 ("fuse: extend init flags")
Cc: <stable@vger.kernel.org> # v5.17
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/fuse/inode.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 660be31aaabc..f19d748890f0 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1134,7 +1134,10 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
process_init_limits(fc, arg);
if (arg->minor >= 6) {
- u64 flags = arg->flags | (u64) arg->flags2 << 32;
+ u64 flags = arg->flags;
+
+ if (flags & FUSE_INIT_EXT)
+ flags |= (u64) arg->flags2 << 32;
ra_pages = arg->max_readahead / PAGE_SIZE;
if (flags & FUSE_ASYNC_READ)
--
2.30.9