diff options
| author | Tong Zhang <ztong0001@gmail.com> | 2022-01-30 00:40:55 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-01-30 10:56:58 +0300 |
| commit | e7f1e8834b2b2144dfbe0b2235d05e4f6f95882e (patch) | |
| tree | 86f8b9728b800bf46ac901916cffaa654fbb1a51 | |
| parent | 6cb917411e028dcb66ce8f5db1b47361b78d7d3f (diff) | |
| download | linux-e7f1e8834b2b2144dfbe0b2235d05e4f6f95882e.tar.xz | |
binfmt_misc: fix crash when load/unload module
We should unregister the table upon module unload otherwise something
horrible will happen when we load binfmt_misc module again. Also note
that we should keep value returned by register_sysctl_mount_point() and
release it later, otherwise it will leak.
Also, per Christian's comment, to fully restore the old behavior that
won't break userspace the check(binfmt_misc_header) should be
eliminated.
To reproduce:
modprobe binfmt_misc
modprobe -r binfmt_misc
modprobe binfmt_misc
modprobe -r binfmt_misc
modprobe binfmt_misc
resulting in
modprobe: can't load module binfmt_misc (kernel/fs/binfmt_misc.ko): Cannot allocate memory
and an unhappy kernel:
binfmt_misc: Failed to create fs/binfmt_misc sysctl mount point
binfmt_misc: Failed to create fs/binfmt_misc sysctl mount point
BUG: unable to handle page fault for address: fffffbfff8004802
Call Trace:
init_misc_binfmt+0x2d/0x1000 [binfmt_misc]
Link: https://lkml.kernel.org/r/20220124181812.1869535-2-ztong0001@gmail.com
Fixes: 3ba442d5331f ("fs: move binfmt_misc sysctl to its own file")
Signed-off-by: Tong Zhang <ztong0001@gmail.com>
Co-developed-by: Christian Brauner<brauner@kernel.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/binfmt_misc.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index ddea6acbddde..c07f35719ee3 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -817,20 +817,20 @@ static struct file_system_type bm_fs_type = { }; MODULE_ALIAS_FS("binfmt_misc"); +static struct ctl_table_header *binfmt_misc_header; + static int __init init_misc_binfmt(void) { int err = register_filesystem(&bm_fs_type); if (!err) insert_binfmt(&misc_format); - if (!register_sysctl_mount_point("fs/binfmt_misc")) { - pr_warn("Failed to create fs/binfmt_misc sysctl mount point"); - return -ENOMEM; - } + binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc"); return 0; } static void __exit exit_misc_binfmt(void) { + unregister_sysctl_table(binfmt_misc_header); unregister_binfmt(&misc_format); unregister_filesystem(&bm_fs_type); } |