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fuse: Apply flags2 only when userspace set the FUSE_INIT_EXT

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commit 3066ff9347 upstream.

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: 53db28933e ("fuse: extend init flags")
Cc: <stable@vger.kernel.org> # v5.17
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bernd Schubert 2022-04-15 13:53:56 +02:00 committed by Greg Kroah-Hartman
parent c5f559674c
commit b1b3f504dc
1 changed files with 4 additions and 1 deletions
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5
fs/fuse/inode.c
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@ -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)