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 <[email protected]>
---
drivers/isdn/capi/kcapi.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/isdn/capi/kcapi.c b/drivers/isdn/capi/kcapi.c
index cb0afe897162..7313454e403a 100644
--- a/drivers/isdn/capi/kcapi.c
+++ b/drivers/isdn/capi/kcapi.c
@@ -480,6 +480,11 @@ int detach_capi_ctr(struct capi_ctr *ctr)
ctr_down(ctr, CAPI_CTR_DETACHED);
+ if (ctr->cnr < 1 || ctr->cnr - 1 >= CAPI_MAXCONTR) {
+ err = -EINVAL;
+ goto unlock_out;
+ }
+
if (capi_controller[ctr->cnr - 1] != ctr) {
err = -EINVAL;
goto unlock_out;
--
2.25.1
On Fri, Oct 8, 2021 at 8:58 AM Xiaolong Huang
<[email protected]> wrote:
>
> 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 <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Hello:
This patch was applied to netdev/net.git (master)
by Jakub Kicinski <[email protected]>:
On Fri, 8 Oct 2021 14:58:30 +0800 you wrote:
> 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);
>
> [...]
Here is the summary with links:
- isdn: cpai: check ctr->cnr to avoid array index out of bound
https://git.kernel.org/netdev/net/c/1f3e2e97c003
You are awesome, thank you!
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