On 6/23/25 01:25, Mengbiao Xiong wrote:
> When CONFIG_CRYPTO_DEV_CCP_DEBUGFS is enabled, rebinding
> the ccp device causes the following crash:
>
> $ echo '0000:0a:00.2' > /sys/bus/pci/drivers/ccp/unbind
> $ echo '0000:0a:00.2' > /sys/bus/pci/drivers/ccp/bind
>
> [ 204.976930] BUG: kernel NULL pointer dereference, address: 0000000000000098
> [ 204.978026] #PF: supervisor write access in kernel mode
> [ 204.979126] #PF: error_code(0x0002) - not-present page
> [ 204.980226] PGD 0 P4D 0
> [ 204.981317] Oops: Oops: 0002 [#1] SMP NOPTI
> ...
> [ 204.997852] Call Trace:
> [ 204.999074] <TASK>
> [ 205.000297] start_creating+0x9f/0x1c0
> [ 205.001533] debugfs_create_dir+0x1f/0x170
> [ 205.002769] ? srso_return_thunk+0x5/0x5f
> [ 205.004000] ccp5_debugfs_setup+0x87/0x170 [ccp]
> [ 205.005241] ccp5_init+0x8b2/0x960 [ccp]
> [ 205.006469] ccp_dev_init+0xd4/0x150 [ccp]
> [ 205.007709] sp_init+0x5f/0x80 [ccp]
> [ 205.008942] sp_pci_probe+0x283/0x2e0 [ccp]
> [ 205.010165] ? srso_return_thunk+0x5/0x5f
> [ 205.011376] local_pci_probe+0x4f/0xb0
> [ 205.012584] pci_device_probe+0xdb/0x230
> [ 205.013810] really_probe+0xed/0x380
> [ 205.015024] __driver_probe_device+0x7e/0x160
> [ 205.016240] device_driver_attach+0x2f/0x60
> [ 205.017457] bind_store+0x7c/0xb0
> [ 205.018663] drv_attr_store+0x28/0x40
> [ 205.019868] sysfs_kf_write+0x5f/0x70
> [ 205.021065] kernfs_fop_write_iter+0x145/0x1d0
> [ 205.022267] vfs_write+0x308/0x440
> [ 205.023453] ksys_write+0x6d/0xe0
> [ 205.024616] __x64_sys_write+0x1e/0x30
> [ 205.025778] x64_sys_call+0x16ba/0x2150
> [ 205.026942] do_syscall_64+0x56/0x1e0
> [ 205.028108] entry_SYSCALL_64_after_hwframe+0x76/0x7e
> [ 205.029276] RIP: 0033:0x7fbc36f10104
> [ 205.030420] Code: 89 02 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8d 05 e1 08 2e 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 41 54 55 49 89 d4 53 48 89 f5
>
> This patch sets ccp_debugfs_dir to NULL after destroying it in
> ccp5_debugfs_destroy, allowing the directory dentry to be
> recreated when rebinding the ccp device.
>
> Tested on AMD Ryzen 7 1700X.
>
> Fixes: 3cdbe346ed3f ("crypto: ccp - Add debugfs entries for CCP information")
> Signed-off-by: Mengbiao Xiong <xisme1998@xxxxxxxxx>
> ---
> drivers/crypto/ccp/ccp-debugfs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/crypto/ccp/ccp-debugfs.c b/drivers/crypto/ccp/ccp-debugfs.c
> index a1055554b..0d432f3c4 100644
> --- a/drivers/crypto/ccp/ccp-debugfs.c
> +++ b/drivers/crypto/ccp/ccp-debugfs.c
> @@ -320,4 +320,5 @@ void ccp5_debugfs_setup(struct ccp_device *ccp)
> void ccp5_debugfs_destroy(void)
> {
> debugfs_remove_recursive(ccp_debugfs_dir);
> + ccp_debugfs_dir = NULL;
Hmmm... it seems like this should be protected by the mutex similar to how
ccp5_debugfs_setup() is, right?
Maybe something like:
mutex_lock(&ccp_debugfs_lock);
if (ccp_debugfs_dir) {
debugfs_remove_recursive(ccp_debugfs_dir);
ccp_debugfs_dir = NULL;
}
mutex_unlock(&ccp_debugfs_lock);
That should also fix the issue, thoughts?
Thanks,
Tom
> }
