kernel/git/stable/linux.git/drivers/isdn/capi/kcapi.c, branch master

net: remove ISDN subsystem and Bluetooth CMTP

2026-04-23T17:24:02+00:00

Remove the ISDN (mISDN, CAPI) subsystem and Bluetooth CMTP protocol from the kernel tree. ISDN is a pretty old technology and it's unclear whether anyone still uses it. I went over the last few years of git history and all the commits are either tree-wide conversions or syzbot/static analyzer fixes. When we discussed removal in the past IIRC there were some concerns about ISDN still being used in parts of Germany. Unfortunately, the code base is quite old, none of the current maintainers are familiar with it and AI tools will have a field day finding bugs here. Delete this code and preserve it in an out-of-tree repository for any remaining users: https://github.com/linux-netdev/mod-orphan UAPI constants AF_ISDN/PF_ISDN and the SELinux isdn_socket class are preserved for ABI stability, but the rest of uAPI is removed. Signed-off-by: Jakub Kicinski Acked-by: Greg Kroah-Hartman Acked-by: Stephen Hemminger Acked-by: Luiz Augusto von Dentz Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260421022108.1299678-1-kuba@kernel.org Signed-off-by: Paolo Abeni

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

isdn: kcapi: add WQ_PERCPU to alloc_workqueue users

2025-11-11T02:14:20+00:00

Currently if a user enqueues a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistency cannot be addressed without refactoring the API. alloc_workqueue() treats all queues as per-CPU by default, while unbound workqueues must opt-in via WQ_UNBOUND. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they’re needed and reducing noise when CPUs are isolated. This continues the effort to refactor workqueue APIs, which began with the introduction of new workqueues and a new alloc_workqueue flag in: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Link: https://patch.msgid.link/20251107134452.198378-1-marco.crivellari@suse.com Signed-off-by: Jakub Kicinski

isdn: kcapi: don't build unused procfs code

2024-04-06T05:11:28+00:00

The procfs file is completely unused without CONFIG_PROC_FS but causes a compile time warning: drivers/isdn/capi/kcapi_proc.c:97:36: error: unused variable 'seq_controller_ops' [-Werror,-Wunused-const-variable] static const struct seq_operations seq_controller_ops = { drivers/isdn/capi/kcapi_proc.c:104:36: error: unused variable 'seq_contrstats_ops' [-Werror,-Wunused-const-variable] drivers/isdn/capi/kcapi_proc.c:179:36: error: unused variable 'seq_applications_ops' [-Werror,-Wunused-const-variable] drivers/isdn/capi/kcapi_proc.c:186:36: error: unused variable 'seq_applstats_ops' [-Werror,-Wunused-const-variable] Remove the file from the build in that config and make the calls into it conditional instead. Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20240403080702.3509288-27-arnd@kernel.org Signed-off-by: Jakub Kicinski

isdn: kcapi: replace deprecated strncpy with strscpy_pad

2023-10-02T18:07:02+00:00

`strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. `buf` is used in this context as a data buffer with 64 bytes of memory to be occupied by capi_manufakturer. We see the caller capi20_get_manufacturer() passes data.manufacturer as its `buf` argument which is then later passed over to user space. Due to this, let's keep the NUL-padding that strncpy provided by using strscpy_pad so as to not leak any stack data. | cdev->errcode = capi20_get_manufacturer(data.contr, data.manufacturer); | if (cdev->errcode) | return -EIO; | | if (copy_to_user(argp, data.manufacturer, | sizeof(data.manufacturer))) | return -EFAULT; Perhaps this would also be a good instance to use `strtomem_pad` for but in my testing the compiler was not able to determine the size of `buf` -- even with all the hints. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230922-strncpy-drivers-isdn-capi-kcapi-c-v1-1-55fcf8b075fb@google.com Signed-off-by: Kees Cook

isdn: move from strlcpy with unused retval to strscpy

2022-08-23T00:54:03+00:00

Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Signed-off-by: Wolfram Sang Link: https://lore.kernel.org/r/20220818210023.6889-1-wsa+renesas@sang-engineering.com Signed-off-by: Jakub Kicinski

isdn: cpai: no need to initialise statics to 0

2021-12-13T14:05:00+00:00

Static variables do not need to be initialised to 0, because compiler will initialise all uninitialised statics to 0. Thus, remove the unneeded initializations. Signed-off-by: Jason Wang Signed-off-by: David S. Miller

isdn: cpai: check ctr->cnr to avoid array index out of bound

2021-10-08T23:52:58+00:00

The cmtp_add_connection() would add a cmtp session to a controller and run a kernel thread to process cmtp. __module_get(THIS_MODULE); session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d", session->num); During this process, the kernel thread would call detach_capi_ctr() to detach a register controller. if the controller was not attached yet, detach_capi_ctr() would trigger an array-index-out-bounds bug. [ 46.866069][ T6479] UBSAN: array-index-out-of-bounds in drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]' [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted 5.15.0-rc2+ #8 [ 46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 46.870107][ T6479] Call Trace: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479] __ubsan_handle_out_of_bounds.cold+0x43/0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479] Signed-off-by: Xiaolong Huang Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20211008065830.305057-1-butterflyhuangxx@gmail.com Signed-off-by: Jakub Kicinski

isdn: capi: fix mismatched prototypes

2021-03-22T23:51:11+00:00

gcc-11 complains about a prototype declaration that is different from the function definition: drivers/isdn/capi/kcapi.c:724:44: error: argument 2 of type ‘u8 *’ {aka ‘unsigned char *’} declared as a pointer [-Werror=array-parameter=] 724 | u16 capi20_get_manufacturer(u32 contr, u8 *buf) | ~~~~^~~ In file included from drivers/isdn/capi/kcapi.c:13: drivers/isdn/capi/kcapi.h:62:43: note: previously declared as an array ‘u8[64]’ {aka ‘unsigned char[64]’} 62 | u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]); | ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/isdn/capi/kcapi.c:790:38: error: argument 2 of type ‘u8 *’ {aka ‘unsigned char *’} declared as a pointer [-Werror=array-parameter=] 790 | u16 capi20_get_serial(u32 contr, u8 *serial) | ~~~~^~~~~~ In file included from drivers/isdn/capi/kcapi.c:13: drivers/isdn/capi/kcapi.h:64:37: note: previously declared as an array ‘u8[8]’ {aka ‘unsigned char[8]’} 64 | u16 capi20_get_serial(u32 contr, u8 serial[CAPI_SERIAL_LEN]); | ~~~^~~~~~~~~~~~~~~~~~~~~~~ Change the definition to make them match. Signed-off-by: Arnd Bergmann Signed-off-by: David S. Miller

isdn: capi: dead code removal

2019-12-11T08:12:38+00:00

The staging isdn drivers are gone, and CONFIG_BT_CMTP is now the only user. This means a lot of the code in the subsystem has no remaining callers and can be removed. Change the capi user space front-end to be part of kernelcapi, and the combined module to only be compiled if BT_CMTP is also enabled, then remove the interfaces that have no remaining callers. As the notifier list and the capi_drivers list have no callers outside of kcapi.c, the implementation gets much simpler. Some definitions from the include/linux/*.h headers are only needed internally and are moved to kcapi.h. Acked-by: David Miller Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20191210210455.3475361-2-arnd@arndb.de Signed-off-by: Greg Kroah-Hartman