From: Eric Biggers <ebiggers@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org,
Alexei Starovoitov <ast@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jeff Vander Stoep <jeffv@google.com>,
Jessica Yu <jeyu@kernel.org>, Kees Cook <keescook@chromium.org>,
Luis Chamberlain <mcgrof@kernel.org>, NeilBrown <neilb@suse.com>,
stable@vger.kernel.org
Subject: [PATCH v3 2/5] fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once()
Date: Sat, 14 Mar 2020 14:34:23 -0700 [thread overview]
Message-ID: <20200314213426.134866-3-ebiggers@kernel.org> (raw)
In-Reply-To: <20200314213426.134866-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
After request_module(), nothing is stopping the module from being
unloaded until someone takes a reference to it via try_get_module().
The WARN_ONCE() in get_fs_type() is thus user-reachable, via userspace
running 'rmmod' concurrently.
Since WARN_ONCE() is for kernel bugs only, not for user-reachable
situations, downgrade this warning to pr_warn_once().
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: NeilBrown <neilb@suse.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/filesystems.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/filesystems.c b/fs/filesystems.c
index 77bf5f95362da..90b8d879fbaf3 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -272,7 +272,9 @@ struct file_system_type *get_fs_type(const char *name)
fs = __get_fs_type(name, len);
if (!fs && (request_module("fs-%.*s", len, name) == 0)) {
fs = __get_fs_type(name, len);
- WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name);
+ if (!fs)
+ pr_warn_once("request_module fs-%.*s succeeded, but still no fs?\n",
+ len, name);
}
if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) {
--
2.25.1
next prev parent reply other threads:[~2020-03-15 2:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-14 21:34 [PATCH v3 0/5] module autoloading fixes and cleanups Eric Biggers
2020-03-14 21:34 ` [PATCH v3 1/5] kmod: make request_module() return an error when autoloading is disabled Eric Biggers
2020-03-18 16:03 ` Jessica Yu
2020-03-14 21:34 ` Eric Biggers [this message]
2020-03-17 22:30 ` [PATCH v3 2/5] fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() Sasha Levin
2020-03-18 15:09 ` Jessica Yu
2020-03-18 22:55 ` Eric Biggers
2020-03-18 15:43 ` Jessica Yu
2020-03-18 22:54 ` Eric Biggers
2020-03-14 21:34 ` [PATCH v3 3/5] docs: admin-guide: document the kernel.modprobe sysctl Eric Biggers
2020-03-14 21:34 ` [PATCH v3 4/5] selftests: kmod: fix handling test numbers above 9 Eric Biggers
2020-03-14 21:34 ` [PATCH v3 5/5] selftests: kmod: test disabling module autoloading Eric Biggers
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