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| author | Max Kellermann <max.kellermann@ionos.com> | 2024-11-19 01:28:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-01-17 15:34:36 +0300 |
| commit | e4b168c64da06954be5d520f6c16469b1cadc069 (patch) | |
| tree | e6f45be1001bf4be4e5b41efa9c4b2b416451535 /fs/ceph | |
| parent | c63962be84ef9c4f32e2a57404ceeda330ff3beb (diff) | |
| download | linux-e4b168c64da06954be5d520f6c16469b1cadc069.tar.xz | |
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 6.1: pr_warn() is still in use]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/ceph')
| -rw-r--r-- | fs/ceph/mds_client.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index da9fcf48ab6c..741ca7d10032 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2447,12 +2447,11 @@ retry: if (pos < 0) { /* - * A rename didn't occur, but somehow we didn't end up where - * we thought we would. Throw a warning and try again. + * The path is longer than PATH_MAX and this function + * cannot ever succeed. Creating paths that long is + * possible with Ceph, but Linux cannot use them. */ - pr_warn("build_path did not end path lookup where " - "expected, pos is %d\n", pos); - goto retry; + return ERR_PTR(-ENAMETOOLONG); } *pbase = base; |