It was first found on HUAWEI Kirin 9006C platform with a builtin xhci controller during stress cycle test(stress-ng, glmark2, x11perf, S4...).

phase one: [26788.706878] PM: dpm_run_callback(): platform_pm_thaw+0x0/0x68 returns -12 [26788.706878] PM: Device xhci-hcd.1.auto failed to thaw async: error -12 ... phase two: [28650.583496] [2023:01:19 04:43:29]Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028 ... [28650.583526] user pgtable: 4k pages, 39-bit VAs, pgdp=000000027862a000 [28650.583557] [0000000000000028] pgd=0000000000000000 ... [28650.583587] pc : xhci_suspend+0x154/0x5b0 [28650.583618] lr : xhci_suspend+0x148/0x5b0 [28650.583618] sp : ffffffc01c7ebbd0 [28650.583618] x29: ffffffc01c7ebbd0 x28: ffffffec834d0000 [28650.583618] x27: ffffffc0106a3cc8 x26: ffffffb2c540c848 [28650.583618] x25: 0000000000000000 x24: ffffffec82ee30b0 [28650.583618] x23: ffffffb43b31c2f8 x22: 0000000000000000 [28650.583618] x21: 0000000000000000 x20: ffffffb43b31c000 [28650.583648] x19: ffffffb43b31c2a8 x18: 0000000000000001 [28650.583648] x17: 0000000000000803 x16: 00000000fffffffe [28650.583648] x15: 0000000000001000 x14: ffffffb150b67e00 [28650.583648] x13: 00000000f0000000 x12: 0000000000000001 [28650.583648] x11: 0000000000000000 x10: 0000000000000a80 [28650.583648] x9 : ffffffc01c7eba00 x8 : ffffffb43ad10ae0 [28650.583648] x7 : ffffffb84cd98dc0 x6 : 0000000cceb6a101 [28650.583679] x5 : 00ffffffffffffff x4 : 0000000000000001 [28650.583679] x3 : 0000000000000011 x2 : 0000000000e2cfa8 [28650.583679] x1 : 00000000823535e1 x0 : 0000000000000000

gdb: (gdb) l *(xhci_suspend+0x154) 0xffffffc010b6cd44 is in xhci_suspend (/.../drivers/usb/host/xhci.c:854). 849 { 850 struct xhci_ring *ring; 851 struct xhci_segment *seg; 852 853 ring = xhci->cmd_ring; 854 seg = ring->deq_seg; (gdb) disassemble 0xffffffc010b6cd44 ... 0xffffffc010b6cd40 <+336>: ldr x22, [x19, #160] 0xffffffc010b6cd44 <+340>: ldr x20, [x22, #40] 0xffffffc010b6cd48 <+344>: mov w1, #0x0 // #0

During phase one, platform_pm_thaw called xhci_plat_resume which called xhci_resume. The rest possible calling routine might be xhci_resume->xhci_init->xhci_mem_init, and xhci->cmd_ring was cleaned in xhci_mem_cleanup before xhci_mem_init returned -ENOMEM.

During phase two, systemd was tring to hibernate again and called xhci_suspend, then xhci_clear_command_ring dereferenced xhci->cmd_ring which was already NULL.

So if xhci->cmd_ring is NULL, xhci_clear_command_ring just return.

Fixes: 898213200cba ("xhci: Fix command ring replay after resume.") Cc: stable@vger.kernel.org # 2.6.27+ Co-developed-by: sunke sunke@kylinos.cn Signed-off-by: sunke sunke@kylinos.cn Signed-off-by: Hongyu Xie xiehongyu1@kylinos.cn --- drivers/usb/host/xhci.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 6183ce8574b1..faa0a63671f6 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -920,6 +920,11 @@ static void xhci_clear_command_ring(struct xhci_hcd *xhci) struct xhci_ring *ring; struct xhci_segment *seg;

+ if (!xhci->cmd_ring) { + xhci_err(xhci, "Empty cmd ring"); + return; + } + ring = xhci->cmd_ring; seg = ring->deq_seg; do {