Max Kellermann c47ed91156 ceph: give up on paths longer than PATH_MAX ...

commit 550f7ca98ee028a606aa75705a7e77b1bd11720f upstream.

If the full path to be built by ceph_mdsc_build_path() happens to be
longer than PATH_MAX, then this function will enter an endless (retry)
loop, effectively blocking the whole task.  Most of the machine
becomes unusable, making this a very simple and effective DoS
vulnerability.

I cannot imagine why this retry was ever implemented, but it seems
rather useless and harmful to me.  Let's remove it and fail with
ENAMETOOLONG instead.

Cc: stable@vger.kernel.org
Reported-by: Dario Weißer <dario@cure53.de>
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Alex Markuze <amarkuze@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
[idryomov@gmail.com: backport to 6.6: pr_warn() is still in use]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2025-01-09 13:31:54 +01:00

..

acl.c

…

addr.c

…

cache.c

…

cache.h

…

caps.c

…

ceph_frag.c

…

crypto.c

…

crypto.h

…

debugfs.c

…

dir.c

…

export.c

…

file.c

ceph: allocate sparse_ext map only for sparse reads

2025-01-02 10:32:00 +01:00

inode.c

…

io.c

…

io.h

…

ioctl.c

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ioctl.h

…

Kconfig

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locks.c

…

Makefile

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mds_client.c

ceph: give up on paths longer than PATH_MAX

2025-01-09 13:31:54 +01:00

mds_client.h

…

mdsmap.c

…

metric.c

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metric.h

…

quota.c

…

snap.c

…

strings.c

…

super.c

…

super.h

…

util.c

…

xattr.c

…